20 minutes, then stopCostume 1Wed 14 October1 / 4
Choose one of these two
1 Pokémon 2 everyday life — do sheet 1 or sheet 2, then everyone does 3 and 4
Name Date
1 · Pokémon — how many hits?How many more hits? = HP left ÷ damage per hit. The game numbers are made up.
If there is a remainder, you need one more hit (round up).
Example · already workedHP left 150. Each hit does about 40. How many more hits?
① Estimate: 40 x 3 = 120 (still left), 40 x 4 = 160 (over 150)
② 150 ÷ 40 = 3 remainder 30
③ 30 HP is still left, so one more hit → 4 hits
1HP left 215. Each hit does 35. How many more hits? Use long division.
How much HP do 6 hits take off? Is that enough?
2HP left 312. Each hit does about 48. Say your estimate out loud first (48 ≈ 50, 312 ≈ 300), then work it out properly in long division. How many more hits?
3HP left 360. Each hit does a whole number from 40 up to (but not including) 50. How many hits in the luckiest case, and in the unluckiest?
The biggest damage is 49 (it must be less than 50).
2 · Everyday life — petrol for the carKm per litre = distance driven ÷ litres used. The numbers are made up.
Before you divide, say the rough answer out loud first.
Example · already workedA full 50 L tank took the car 650 km. How many km per litre?
① Estimate: 50 x 10 = 500 km. 650 is more → more than 10 km per litre
② 650 ÷ 50 = 13 → 13 km
1A full 45 L tank took the car 540 km. How many km per litre?
Estimate first: 45 L x 10 km = 450 km. 540 is more than that.
2A full 38 L tank took the car 456 km. First say "more or less than 10 km per litre?", then work out the km per litre in long division.
3A car goes 13 km on 1 litre and has to drive 200 km. What is the least number of whole litres that is enough?
How far do 15 litres go?
3 · From here, everyone
4Work out 678 ÷ 32 in long division.
Round 32 to 30 and make your estimate.
5You work out 208 ÷ 26 by rounding 26 to 30 and guessing 6. Take 26 x 6 away from 208: what is left? Then fix the quotient and give the correct answer.
See how many times the divisor fits into the remainder and you can fix it in one go.
6You buy sweets at 38 yen each with 1,500 yen.
A Round 38 to 40 and say roughly how many you can buy.
B Use long division to find how many you can buy and how many yen are left.
38 yen is cheaper than 40, so the real number is a little more than the estimate.
4 · Rounding and estimating
7Round 6,451 to the nearest hundred.
The tens digit is 5. Which way does exactly 5 go?
8Whole numbers that round to 4,300 (nearest hundred): write their range using "at least" and "less than".
Just below 4,300 is 4,200 and just above is 4,400. Where are the midpoints?
9You have 1,500 yen and buy things at 398, 249 and 505 yen. Round each up to the hundred, estimate the total, and say whether the money is enough.
Rounding up makes it bigger than the real total. If that is still enough, you are safe.