Long Multiplication: 20 × 20

"Long Multiplication Calculator" Calculator

Multiplicand (number to be multiplied)

Multiplier (number to multiply by)

What is 20 × 20?

Answer

20 × 20 = 400

20 × 20 is a square: a number multiplied by itself, so 400 is the square of 20. Below, 20 is multiplied by 20 in a column, digit by digit.

20 × 20 in a Column

The multiplicand goes on top, the multiplier underneath, both aligned on the right. Only one digit of the multiplier is not zero, and it stands for 20, so there is a single partial product and the answer goes straight under the line.

  20
× 20
 400
20 × 20 = 400

Step-by-Step Solution

Step 1: The last digit of the multiplier is 0, so this partial product is 0 and adds nothing to the total.

Step 2: The next digit of the multiplier is 2, and it stands for 20: 20 × 20 = 400.

  • 0 × 2 = 0. Write 0.
  • 2 × 2 = 4. Write 4.

20 × 20

=

400

Check It, and What It Is Not

Check by dividing back. Multiplication and division undo each other, so 400 ÷ 20 = 20 must come out exactly, with no remainder.

Fractions are a different calculation. Both factors here are whole numbers; for 2/3 or 2 3/4 use the fraction multiplication calculator, which multiplies numerators and denominators separately.

20 × 20 is a number, not an area. If those are the sides of a room in feet, the answer is 400 square feet — the same arithmetic, a different question, and it is answered by the square footage calculator.

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About "Long Multiplication Calculator" Calculator

This calculator multiplies two whole numbers the way it is done on paper: digit by digit, carrying where the column overflows, then adding the partial products together. For example, it can help you find out what is 20 × 20? (The answer is: 400). Enter the multiplicand (e.g. '20') and the multiplier (e.g. '20') and hit the button. The order of the two numbers never matters: swapping the factors leaves the product unchanged, so either one can go on top. Fractions and mixed numbers belong to the fraction multiplication calculator, and the reverse operation is long division.

"Long Multiplication Calculator" Calculator

Multiplicand (number to be multiplied)

Multiplier (number to multiply by)

Products of 20

MultiplicationProduct
20 × 120
20 × 240
20 × 360
20 × 480
20 × 5100
20 × 6120
20 × 7140
20 × 8160
20 × 9180
20 × 10200
20 × 11220
20 × 12240
20 × 20400

FAQ

What is 20 × 20?

20 × 20 = 400

Is 400 a square number?

Yes. 20 × 20 = 400, so 400 is the square of 20. A square is simply a number multiplied by itself, which is why both factors here are the same.

How do you check that 20 × 20 = 400?

Divide the product back by one of the factors: 400 ÷ 20 = 20 exactly, with no remainder. Multiplication and division undo each other, which is what makes this check work.

What are the partial products of 20 × 20?

Only one of them counts: every other digit of 20 is a zero and contributes nothing, so the work comes down to 20 × 20 = 400, with nothing left to add.

See Also