Say "about ..." out loud first. Then calculate, and check they are close.Loud enough for a parent to hear. An estimate you did not say is not an estimate.
Question 1 is already done for youRound 4,268 to the nearest hundred. (three ways)
Round down zero out the tens and ones → 4,200
Round up if the tens and ones are not 0, add 1 to the hundreds → 4,300
Ordinary rounding the tens digit is 6, which is 5 or more, so up → 4,300
Your turn from here
2Round 7,218 to the nearest thousand three ways: round down, round up, and ordinary rounding.
To the nearest thousand, look at the hundreds.
3You buy a 489-yen book and a 302-yen notebook. Say "about ..." out loud first, then round each to the nearest hundred and estimate the total.
4You spend 2,896 yen out of 5,203 yen. Round each to the nearest hundred and estimate what is left.
"At least", "at most" and "less than"110 or more (at least) … includes 110 and goes up
110 or less (at most) … includes 110 and goes down
less than 110 … does not include 110 and goes down
The 5 in the middleDoes 4,550 round to 4,500 (nearest hundred)?
Treating the tens digit 5 as "round down" and saying 4,500 → 5 rounds up. 4,550 → 4,600. So 4,550 is not in the range for 4,500 (at least 4,450 and less than 4,550).
5The whole numbers that round to 300 (nearest ten): write their range two ways.
(1) using "at least" and "less than" (2) using "at least" and "at most"
Draw a number line and look either side of 300.
6Whole numbers that round to 4,500 (nearest hundred): write the range using "at least" and "less than". Also write the largest whole number.
7A ride lets in people who are "at least 110 cm and less than 140 cm" tall. Can each of these ride? Write yes or no.
(1) 109 cm (2) 110 cm (3) 140 cm (4) 139 cm
Pick the method from the storyMaking sure there is enough → round up
How many you can buy, how many fit → round down
Wanting a rough comparison → ordinary rounding
8235 people ride in buses that hold 40 each. How many buses are needed? Also write which rounding method you used.
When you need to be sure there is enough…
9Sweets cost 85 yen each. You buy as many as you can with 700 yen. How many?
10A town has 27,418 people.
(1) Round to the nearest thousand.
(2) Round keeping only the first digit.
11You buy 31 items at 78 yen each. Round both numbers, keeping only the first digit, and estimate the cost.
12You buy things at 305, 198, 287 and 156 yen, and have 1,000 yen. Round each up to the hundred. Can you say it is enough? Then add them exactly to check whether it really is.
13About how much is 4,187 + 3,912? Say it out loud before calculating, then choose.
A 800 B 8,000 C 80,000
Write why you chose it.