Dividing to an approximate answer

When a division doesn't come out exactly, give an approximate answer. To one decimal place (the tenths), divide to the second decimal place; to two decimal places (the hundredths), divide to the third; then look at that extra digit: 0 to 4, drop it; 5 to 9, add one to the digit before it (rounding). 20 ÷ 7 = 2.85…; to one decimal place the second digit is 5, so round up: about 2.9. Or look at the remainder: 20 ÷ 7 leaves 0.4 at 2.8, and 0.4 is more than half of 7 tenths (0.35), so round up. In a word problem, think about the situation: to pack everything, one more box is needed even when it won't be full (round up): 18 ÷ 4 = 4.5 needs 5 boxes; to make whole things, a part that isn't enough doesn't count (round down): 18 ÷ 4 = 4.5 makes only 4. Check: the answer times the divisor should be close to the number divided: 2.9 × 7 = 20.3.