Best estimate is 20 x 40 = 800 Actual answer is 22 x 39 = 858
The closest estimate is the exact value.39*2 = (40 - 1)*2 = 80 - 2 = 78Then 39*22 = 39*2*11 = 78*11 = 858[Multiplication by 11 give the digits 7, 7+8 and 8 - with the carry overs applied to the answer.]
Assuming that you can only use each number once, then one solution is :- 6 x (22 - 2 - 39/3) = 6 x (20 - 13) = 6 x 7 = 42
39. 78 = 2 x 3 x 13 117 = 32 x 13 156 = 22 x 3 x 13 gcf = 3 x 13 = 39
0 x 39 = 0 1 x 39 = 39 2 x 39 = 78 3 x 39 = 117 4 x 39 = 156 5 x 39 = 195 6 x 39 = 234 7 x 39 = 273 8 x 39 = 312 9 x 39 = 351 10 x 39 = 390
22 as a percentage of 39 is: 22/39 times 100 = 56.410256% repeating decimal 0.410256
39/1
39 - 22 = 1717 ÷ 39 = 0.43590.4359 * 100(%) = 43.59%
The greatest common factor of 22 and 39 is 1
39 = 1 x 39, 3 x 13, 13 x 3, 39 x 1.
x=3 (39)(x) = (39)(3) = 117
(39 x 26) + (39 x 13) = 39 x 39 = 1521