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45 × 11 is really 45 × 10 plus 45 × 1, so 450 + 45. The 4 and 5 stay on the ends, and the 4 + 5 lands in the middle because that's where the two copies overlap.
Three tricks that make hard-looking sums easy. Learn them, then challenge a grown-up to a race with the calculator app. You'll win.
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Nothing sharp, nothing hot, nowhere far. Tell someone what you're up to, then go ahead and do it on your own.
5 steps. Tap one when it's done.
45 × 11 is really 45 × 10 plus 45 × 1, so 450 + 45. The 4 and 5 stay on the ends, and the 4 + 5 lands in the middle because that's where the two copies overlap.
None of these are magic. Each one is a normal sum rearranged so the hard part disappears. Times 11 is 10 lots plus 1 lot. Times 5 is half of times 10. The finger trick works because every multiple of 9 has digits that add to 9.