N15: round numbers and measures to an appropriate degree of accuracy (e.g. to a specified number of decimal places or significant figures); use inequality notation to specify simple error intervals due to truncation or rounding

What is rounding?

Making a number simpler while keeping its value close to what it was

How to round

Numbers ending in 0,1,2,3,4 are all rounded down (0 is already rounded)

Numbers ending in 5,6,7,8,9 are all rounded up

Round 17.89 to the nearest whole number

18 (it is not always about the exact end of the number, but the number closest to what you will round to - in this case 8, 17.81 would also round to 18)

Write the number 15431 in words

Fifteen thousand four hundred and thirty one

There are 2600 jelly beans in a jar to the nearest hundred. Jack says that there could be 2538 jelly beans in the jar. Mia says that there could be 2640 jelly beans in the jar. Frank says that there could be 2651 jelly beans in the jar. Which of three people is correct?

Jack is not correct as 2538 rounds to 2500 (the 6 is what we are aiming to reach, not 5). Mia is correct as 2640 rounds to 2600. Frank is not correct as 2651 rounds to 2700

Write 83.07718 correct to two decimal places

83.08

Write 6539.46 to 3 significant figures

6540

Write 6.57 to 2 significant figures

6.6