Question 1

What is cross multiplication?

Accepted Answer

Cross multiplication is a method for solving a proportion a/b = c/d. You multiply across the equals sign: a×d = b×c. If one of the four values is unknown, you can solve for it using this equation.

Question 2

How do I solve for x in 3/4 = x/12?

Accepted Answer

Cross multiply: 3 × 12 = 4 × x, so 36 = 4x, and x = 9. The calculator automates this and shows each step.

Question 3

What are common uses of cross multiplication?

Accepted Answer

Scaling recipes, resizing images, calculating map distances, working out unit prices, currency conversion ratios, diluting chemicals, mixing paint, and checking whether two fractions are equivalent.

Question 4

Can the calculator find any missing value?

Accepted Answer

Yes. Leave any one of the four fields (a, b, c, d) blank and the tool will solve for it. If you fill in all four it checks whether the proportion is true and reports the difference.