What approximate value should come in place of the question mark (?) in the following equation? 31.952 − 12.052 + (1987.25 + 13.15) ÷ ? = 900

Approximate the values to get 32 squared minus 12 squared plus 2000 divided by the question mark equals 900. Using the difference of squares identity, a squared minus b squared equals (a plus b)(a minus b), so 32 squared minus 12 squared equals 44 multiplied by 20, which is 880. The equation becomes 880 plus 2000 divided by the question mark equals 900, meaning 2000 divided by the question mark equals 20. This makes the question mark 100.

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