A multiplication formula of two digits multiplied by two digits. One multiplier is 29. If you add two multipliers and the product of multiplication to get 839, how much is the other multiplier? How to calculate

From the multiplication formula, we can know that the product of 29 and a number is 29 times of this number. Add this product to 29 and another multiplier, that is, the sum of (29 + 1) times of that multiplier and 29. In other words, subtracting the difference of 29 from 839 is (29 + 1) times of the other multiplier. Therefore, the other multiplier is (839-29) / (29 + 1) = 27

1,2,3,4 form a two digit multiplication formula. What is the maximum and minimum product

Let these two double digits be AB and CD respectively
(10a+b)(10c+d)=100a*c+10(a*d+b*c)+b*d
Obviously, on the premise that a * C is the largest, when a * D + b * C is the largest, the product is the largest;
If a * C is the minimum, a * D + b * C is the minimum, and the product is the minimum
So to maximize the product, a = 4, C = 3, d = 2, B = 1, these two numbers are 41 and 32
To minimize the product, a = 1, C = 2, d = 4, B = 3, these two numbers are 13 and 24

In the following, fill in 1, 2, 3, 4, 5, 6, 7, 8 and 9 (the number in each formula cannot be repeated, and the numerator of fraction part is less than denominator), so that the value of formula a with fraction is the largest and that of formula B is the smallest

(1) 98745-1236, 12469 + 3578 and 12469 + 3578

() × () = () () () () () fill in nine numbers 1.2.3.4.5.6.7.8.9 in brackets to make the formula true and not repeat the numbers

There are only two solutions,
1738*4=6952
1963*4=7852

A multiplication formula of two digits multiplied by two digits. One multiplier is 29. If you add two multipliers and the product of multiplication to get 839, how much is the other multiplier? How to calculate