Compute 1250 × 48 in your head

Question

Solve in your head. What is 1250 	imes 48? Aim: under 10 seconds.

Accepted Answer

Treat 48 as 50 - 2: 1250 	imes 48 = 1250 	imes 50 - 1250 	imes 2. The 	imes 50 part is "half, then times 100": 1250 	imes 50 = 625 	imes 100 = 62500. The correction is 1250 	imes 2 = 2500. Subtract: 62500 - 2500 = 60000. Takeaway. Factors a touch below 50, like 48 or 49, are 50 - k: do the 	imes 50 halving, then subtract k copies. Rounding to the friendly 50 and correcting keeps everything a one-step adjustment.

Compute 1250 × 48 in your head

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