How to multiply easily two 3-digt numbers in your head, for example 234 x 567:
200 x 500 = 100,000
200 x 60 = 12,000
200 x 7 = 1,400
30 x 500 = 15,000
30 x 60 = 1,800
30 x 7 = 210
4 x 500 = 2,000
4 x 60 = 240
4 x 7 = 28
100,000 + 12,000 + 1,400 + 15,000 + 1,800 + 210 + 2,000 + 240 + 28 = 132,678
