Estimation and Rounding

Have you ever tried to guess how many candies are in a jar? Or quickly figured out about how much money you need to buy a toy and a book? That's estimation! Estimation means finding a number close to the exact answer, quickly: we keep the large place values and drop the small ones.

Rounding is a special way to estimate numbers. When we round, we change a number to make it simpler but still close to the original number.

Rounding to the Nearest Ten

To round a number to the nearest ten, we follow these steps:

1. Look at the ones digit (the last digit)
2. If the ones digit is less than 5 (0, 1, 2, 3, or 4), round down to the previous ten
3. If the ones digit is 5 or more (5, 6, 7, 8, or 9), round up to the next ten

Rounding to the Nearest Hundred

To round a number to the nearest hundred, we follow similar steps:

1. Look at the tens digit (second-to-last digit)
2. If the tens digit is less than 5 (0, 1, 2, 3, or 4), round down to the previous hundred
3. If the tens digit is 5 or more (5, 6, 7, 8, or 9), round up to the next hundred

Rounding to the Nearest Thousand

For rounding to the nearest thousand:

1. Look at the hundreds digit (third-from-last digit)