Printing: use your browser's print (Ctrl+P / ⌘P). The whole week is 12 A4 sheets (6 pieces of paper double-sided) — the same content as the single days.
10 minutes, then stop
Maths B (new unit)Fri 2 October1 / 4
Rounding
About how many? — worked out by a fixed rule
NameDate
The rounding rule
To round to the nearest hundred, look only at the next place down (the tens).
0, 1, 2, 3, 4 → round down (keep it, zeros below)
5, 6, 7, 8, 9 → round up (add 1 to the hundreds, zeros below)
"Round the ones digit" means the same as "round to the nearest ten".
Question 1 is already done for you
Round 2,738 to the nearest hundred.
① The hundreds digit is 7. One place down, the tens digit is 3
② 3 is 4 or less → round down
③ Answer 2,700
Your turn from here
2Round 5,162 to the nearest hundred.
3Round 8,349 to the nearest hundred.
Do not look at the 9 in the ones.
4Round 38,490 to the nearest thousand.
To the nearest thousand means looking at the hundreds — not at the 9.
10 minutes, then stop
Maths B (new unit)Fri 2 October2 / 4
Rounding
NameDate
A common mistake
Round 3,450 to the nearest hundred. Looking at the 0 in the ones: 3,400 → wrong place. The tens digit is 5 → up → 3,500 Round 3,450 to the nearest thousand. 3,450 → 3,500 → 4,000 → never round twice. The hundreds digit is 4 → 3,000
A number exactly in the middle is always rounded up.
5Round 6,950 to the nearest hundred.
What happens when you add 1 to the 9 in the hundreds?
6Round 24,499 to the nearest thousand.
Rounding to the first few digits
First 2 digits → round with the 3rd digit from the left (first 1 digit → the 2nd).
Example 6,380 → the 3rd digit is 8 → up → 6,400
7Round 47,815, keeping the first 2 digits.
10 minutes, then stop
Maths B (new unit)Fri 2 October3 / 4
Rounding
NameDate
"At least" and "less than"
5 or more (at least 5) … includes 5 (5, 6, 7 …) less than 5 … does not include 5 (4, 3, 2 …) 5 or less (at most 5) … includes 5 (5, 4, 3 …)
8Rounded to the nearest ten, a whole number becomes 80. What are the smallest and the largest it could be?
Draw a number line and look either side of 80.
9Numbers that round to 600 (nearest hundred): write their range using "at least" and "less than".
10Which of these round to 3,000 (nearest hundred)? Choose all of them.
A 2,950 B 3,049 C 2,949 D 3,050
10 minutes, then stop
Maths B (new unit)Fri 2 October4 / 4
Rounding
NameDate
Estimating — a rough answer first
11You buy three things: 198 yen, 312 yen and 489 yen. Round each to the nearest hundred and estimate the total.
12You buy things for 289 yen, 305 yen and 196 yen. To know whether 1,000 yen is enough, round each up to the hundred (whatever the tens digit, add 1 to the hundreds) and estimate. Is it enough?
Rounding up makes it bigger than the real total. If that is still enough, you are safe.
13You buy 21 sweets at 48 yen each. Round both numbers, keeping only the first digit, and estimate the cost.
10 minutes, then stop
Costume 2 + correctionsSun 4 October1 / 4
Choose one of these two
1 FPS 2 food — do sheet 1 or sheet 2, then everyone does 3 and 4
NameDate
1 · FPS — kill/death ratio
K/D ratio = kills ÷ deaths: how many kills for each time you were knocked out.
With big numbers, a rough estimate first is quicker.
1Kills 42, deaths 6. What is the K/D ratio?
2Kills 79, deaths 4. Round the kills to the nearest ten and estimate the K/D ratio.
3Kills over a week: 18, 23, 31, 27, 12. Round each to the nearest ten and estimate the total.
10 minutes, then stop
Costume 2 + correctionsSun 4 October2 / 4
Choose one of these two
NameDate
2 · Food — the price of one
Price of one = total price ÷ number of pieces.
When a price is awkward, like 298 yen, round it first and then divide.
1Doughnuts: 6 for 300 yen. How much is one?
2Rice balls: 8 for 396 yen. Round 396 to the nearest hundred and estimate the price of one.
3Biscuits: A is 5 for 298 yen, B is 9 for 452 yen. Round the prices to the nearest ten and estimate which is cheaper per biscuit.
10 minutes, then stop
Costume 2 + correctionsSun 4 October3 / 4
Choose one of these two
NameDate
3 · From here, everyone
4Round 7,648 to the nearest hundred.
5Write every whole number that rounds to 50 (nearest ten).
6You buy 38 packs of gum at 52 yen each. Round both, keeping only the first digit, and estimate the cost.
10 minutes, then stop
Costume 2 + correctionsSun 4 October4 / 4
Choose one of these two
NameDate
4 · Corrections, and one puzzle problem
7Pick one from the corrections notebook and do it again.
Once you can do it the second time, that question is finished.
8Tree planting — trees go along a straight 30 m path, every 5 m from one end to the other, including both ends. How many trees?
Draw it and count the trees one by one.
9Friday's trap once more: round 3,450 to the nearest thousand.
10 minutes a sheet, then stop
Stretch (not recorded)From Sun 4 October, any time1 / 4
Stretch — level up
Not recorded. Getting it wrong is fine.
NameDate
1 · A sunny day and a rainy day [science: weather]
Source 1 — the temperature in a town, every two hours (made-up numbers). 15 mm of rain fell on the rainy day.
Question 1 is already done for you
Sunny day, 10 am: what temperature?
Lines go up 2 °C each. Halfway between lines is the number in between.
The ● at 10 am is on the 20 line → 20 °C
2For the sunny day and the rainy day, write the highest and the lowest temperature.
3Someone says: "The temperature changes more during the rainy day." Is that right? Explain with numbers.
How much it changes = highest − lowest
10 minutes a sheet, then stop
Stretch (not recorded)From Sun 4 October, any time2 / 4
Stretch — level up
NameDate
2 · Water used at home [social studies: water]
Source 1
A (made-up) family of four checked the water they use in a day. Their water bill is 4,800 yen a month.
used for
toilet
bath
laundry
cooking, dishes
other
litres a day
168 L
243 L
131 L
97 L
81 L
Source 2 — water used in one day (made up)
4Round the toilet (168 L) and the laundry (131 L) to the nearest hundred.
Look at the tens: 5 to 9 goes up, 0 to 4 stays.
5Round all five to the nearest hundred and estimate the day's total. Then work out the exact total too.
6Someone says: "If all 50,000 people in the town use as much as one person in this family, home water alone is more than 100 million litres a day." Is that right?
① Per person = total ÷ 4 ② × 50,000 = × 5, then × 10,000 ③ count the zeros
10 minutes a sheet, then stop
Stretch (not recorded)From Sun 4 October, any time3 / 4
Stretch — level up
NameDate
3 · Ready for a disaster [social studies: natural disasters]
Source 1
A (made-up) town leaflet: "Drinking water: 3 L per person per day. Keep 3 days' worth."
item
water, 1 box (2 L × 6)
biscuits, 1 tin
batteries, 1 pack of 4
wind-up radio
price
448 yen
348 yen
249 yen
1,980 yen
Source 2 — shop prices (made up)
7A family of four keeps 3 days' drinking water. How many litres? How many boxes of water?
A box holds six 2 L bottles.
8Today they buy one box of water, one tin of biscuits and one pack of batteries. Round each price to the nearest hundred and estimate the cost.
9Someone says: "The estimate is 900 yen, so 1,000 yen is enough." Is it really enough? Say why.
Look: was each price rounded up, or down?
10 minutes a sheet, then stop
Stretch (not recorded)From Sun 4 October, any time4 / 4