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Divide 1,829 by 31. Estimate first by thinking about 1,800 ÷ 30.

Solution:

Estimate your answer by thinking about how many times 30 could be subtracted from 1,800 or by thinking that 18 ÷ 3 = 6 and so 1,800 ÷ 30 would need a 6 and another zero. 1,800 ÷ 30 = 60, so expect a quotient close to 60. This one may be hard to keep all in your head, so write down as you go.

You're probably tempted to start with a 6, but if you check 6 × 31 = 186, and you're trying to divide into 182, so 6 is too big. Drop down to 5, and place 5 × 31 = 155 under the 182.

Subtract 182 – 155 = 27 and bring down the 9. Three goes into 27 nine times so there's a good chance 31 goes into 279 nine times. Multiply to check it.

If this longer division is giving you trouble, there's more on this in Chapter 4, “Focus on Division.” In the meantime, try Self-Test 2.2.