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Hmm that's interesting - I'd tend to round one of the numbers, whichever is closest to a '5' or '10', to make an 'easier' multiplication, then add / subtract th
by davnicwil 11y ago
Hmm that's interesting - I'd tend to round one of the numbers, whichever is closest to a '5' or '10', to make an 'easier' multiplication, then add / subtract the extra value lost / gained by rounding.
Example 9 x 14 = (<10> * 14) - ([1] * 14) = 140 - 14 = 126
key: <> easier rounded number [] deal with rounding 'error'
- pc86 11y agoI've done that before too, but for whatever reason my mind just defaults to adding two numbers rather than subtracting. Probably either habit or I just find it easier.
- pavel_lishin 11y agoWeird, I did it the other way - 9x10 + 9x4 = 90 + 36 = 126