For problems such as 80 ÷ 16, think of the multiplication problem that corresponds to this. 16 times what is equal to 80? For this you can use the method of trial-and-error. Try plugging in numbers. This is done by choosing any number and multiplying it by the divisor. In this case, we would multiply that number by 16 to get 80. Let’s start with the number 2. Mentally solve that 16 x 2 = [10 x 2] + (6 x 2] = 20 + 12 = 32. 32 is much less than 80, so 2 is too small to be the right answer. Now instead of trying 3 we can skip to 4. 16 x 4 = [10 x 4] + [6 x 4] = 40 + 24 = 64. 64 is still less than 80 but it is closer. Because it is close, we should try the next number; 5. 16 x 5 = [10 x 5] + [6 x 5] = 50 + 30 = 80. 5 is the right answer because 16 x 5 is 80. From this we know that 80 ÷ 16 = 5. Note: You do not always have to start from 2, choose whichever numbers seems like the right answer. If your answer is too low, choose a higher number. If it is too high, go lower.
Practice these problems using this method: Practice 1: 84 ÷ 28 ? x 28 = 84 2 x 28 = 56 This answer is too small, try the next number. (3) x 28 = (84) This answer is just right. 84 ÷ 28 = (3)
Practice 2: 96 ÷ 12 ? x 12 = 96 We can start with 5 here because 12 is a lot smaller than 96 5 x 12 = (60) 5 x 12 is way too small; try skipping to 7. 7 x (12) = (84) This is very close but still not right. Go to next number. 8 x (12) = (96) 96 ÷ 12 = (8)
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