Astuces
Mathématique
108² = 108 + 8 & 8 x 8 = 116 & 64 = 11 664
108 x 109 = 109 + 8 & 8 x 9 = 117 & 72 = 11 772
098² = 98 - 2 & 2 x 2 = 96 & 04 = 9 604
097² = 97 - 3 & 3 x 3 = 94 & 09 = 9 409
997² = 997 - 3 & 3 x 3 = 994 & 009 = 994 009
Les ² se terminant par 5 :
152 = 1 x 2 & 5 x 5 = 2 & 25 = 225
352 = 3 x 4 & 5 x 5 = 12 & 25 = 1 225
352 = 3 x 4 & 5 x 5 = 12 & 25 = 1 225
452 = 4 x 5 & 5 x 5 = 20 & 25 = 2 025
952 = 9 x 10 & 5 x 5 = 90 & 25 = 9 025
952 = 9 x 10 & 5 x 5 = 90 & 25 = 9 025
Multiplication par 11
25 x 11 = 2 (2+5) 5
= 2 7 5
39 x 11 = 3 (3+9) 9
= 3 12 9
= 429
= 2 7 5
39 x 11 = 3 (3+9) 9
= 3 12 9
= 429
111111 x 111111 = 12345678987654321