`# \text {04th5}`
\(9 \times 4 \times 101 + 108 \times 21 - 61 \times 36 \\ = 36 \times 101 +36 \times 63-61 \times 36 \\ = 36 \times (101 + 63 - 61) \\ = 36 \times 103 \\ = 36 \times 100 + 36 \times 3 \\ = 3600+108 \\ = 3708\)
9×4×101+108×21-61×36
9×4×101+108×21-61×36
a.1/6+1/12+1/20+1/30+1/42+............+1/90+1/110
b.2/11*13+2/13*15+2/15*17+..........+2/97*99+2/99*101
c.1/11*16+1/16*21+1/21*26+.................+1/56*61+1/61*66
13=(7X-33) :12
[(7X-31):5]*36= 7236
1+2+3+4+5+...+100+X =5350
80-9(X -4) =35
(3X-21):4+108=114
[(6X-72):2-84]*14=2814
28x+12x=80
249-7(1+x)=200
20-[(x-5)*7 +4]=2
9 phút 36 giây : 4 + 2 giờ 21 phút :9
tính mnhanh
15×3,6+4×61×0,9+1,8×62-7×3,6
15×37×4+120×21×5×12
15×360×40×61×9+180×62-12×210
12,6+13,5+14,4-4,5-3,6-5,4
Biết 4 * 7 = 21; 5 * 9 = 36; 10 * 2 = 18. Vậy 100 * 9 = …
Biết 4 * 7 = 21; 5 * 9 = 36; 10 * 2 = 18. Vậy 100 * 9 = …
4 12 36 108 ... 2916 .
4 +12+36+108+...+2916 .
