Unit 1 Revision WIS Year 8

Round (1782) to the nearest ten.

Answer explanation

To round 1782 to the nearest ten, look at the digit in the ones place (2). Since it is less than 5, we round down. Therefore, 1782 rounded to the nearest ten is 1780.

Round (453) to the nearest hundred.

Answer explanation

To round 453 to the nearest hundred, look at the tens digit (5). Since it's 5 or more, round up. Thus, 453 rounds to 500.

Round (6.789) to one decimal place.

Answer explanation

To round 6.789 to one decimal place, look at the second decimal (8). Since 8 is 5 or greater, round up the first decimal (7) to 8. Thus, 6.789 rounded to one decimal place is 6.8.

Round (0.01234) to three decimal places.

Answer explanation

To round 0.01234 to three decimal places, look at the fourth decimal (3). Since 3 is less than 5, we do not round up. Thus, 0.01234 rounded to three decimal places is 0.012.

Round (12345) to three significant figures.

Answer explanation

To round 12345 to three significant figures, we look at the first three digits (123). The next digit (4) is less than 5, so we keep it as 123. Thus, 12345 rounded to three significant figures is 12300.

Round (0.00678) to two significant figures.

Answer explanation

To round 0.00678 to two significant figures, identify the first two non-zero digits, which are 6 and 7. The next digit (8) is 5 or more, so round up. Thus, 0.00678 rounded to two significant figures is 0.0068.

Round (45.67) to four significant figures.

Answer explanation

To round 45.67 to four significant figures, we note that it already has four significant figures (4, 5, 6, 7). Therefore, the rounded value remains 45.67.

Estimate the value of (28.7 × 11.3).

Answer explanation

To estimate 28.7 × 11.3, round 28.7 to 29 and 11.3 to 11. This gives 29 × 11 = 319. Thus, the estimated value is approximately 319.

Estimate the value of (156.2 ÷ 18.9).

Answer explanation

To estimate 156.2 ÷ 18.9, round 156.2 to 160 and 18.9 to 20. Then, calculate 160 ÷ 20 = 8. This gives a good estimate of the original division.

Answer explanation

To estimate √83.5, we can round it to √81, which is 9. Thus, √83.5 is approximately 9. Adding 6.1 gives us about 15.1. Therefore, the estimated value of (√83.5 + 6.1) is around 15.