Calculate the two numbers in a diamond problem from the product and sum, and display the matching left and right values.

Find two real numbers with the supplied product and sum.

Diamond Problem Formula

A diamond problem uses two numbers that multiply to a product and add to a sum. If the product is P and the sum is S, the two missing numbers can be found with the quadratic formula.

x + y = S
x × y = P
x = (S - sqrt(S² - 4P)) / 2
y = (S + sqrt(S² - 4P)) / 2
  • P = the product, or the number at the top of the diamond
  • S = the sum, or the number at the bottom of the diamond
  • x = the left missing number
  • y = the right missing number
  • S^2 - 4P = the discriminant, which tells whether a real-number answer exists

The calculator takes the product and sum you enter, then solves for the two real numbers that satisfy both equations. It uses a stable equivalent of the quadratic formula to reduce cancellation; displayed decimals are rounded. The left and right values may appear in either order because multiplication and addition are commutative. For example, 3 and 5 give the same product and sum as 5 and 3.

Diamond Problem Result Checks

Discriminant Meaning Result type
S2 - 4P > 0 There are two different real numbers. Example: 2 and 6
S2 - 4P = 0 Both missing numbers are the same. Example: 4 and 4
S2 - 4P < 0 No real-number pair matches the product and sum. No real answer
Product Sum Missing numbers
12 7 3 and 4
18 9 3 and 6
-10 3 -2 and 5
16 8 4 and 4

Example Diamond Problems

Example 1: Product 24 and sum 10

Find two numbers that multiply to 24 and add to 10.

x = (10 - sqrt(10² - 4 × 24)) / 2 = 4
y = (10 + sqrt(10² - 4 × 24)) / 2 = 6

The missing numbers are 4 and 6.

Example 2: Product -12 and sum 1

Find two numbers that multiply to -12 and add to 1.

x = (1 - sqrt(1² - 4 × (- 12))) / 2 = - 3
y = (1 + sqrt(1² - 4 × (- 12))) / 2 = 4

The missing numbers are -3 and 4.

FAQ

What is a diamond problem?

A diamond problem is a math puzzle where you use a product and a sum to find two missing numbers. The two missing numbers must multiply to the product and add to the sum.

Can a diamond problem have negative numbers?

Yes. If the product is negative, one missing number is positive and the other is negative. For example, a product of -10 and a sum of 3 gives -2 and 5.

Why does the calculator say there is no real-number pair?

This happens when the discriminant, S2 - 4P, is negative. In that case, no two real numbers can have both the product and sum you entered. The calculator only returns real-number answers.