Long Multiplication: 21 × 2

"Long Multiplication Calculator" Calculator

Multiplicand (number to be multiplied)

Multiplier (number to multiply by)

What is 21 × 2?

Answer

21 × 2 = 42

21 × 2 and 2 × 21 are the same product — the order of the factors never changes the answer, only the working. Below, 21 is multiplied by 2 in a column, digit by digit.

21 × 2 in a Column

The multiplicand goes on top, the multiplier underneath, both aligned on the right. The multiplier has a single digit, so there is one partial product and the answer goes straight under the line.

 21
× 2
 42
21 × 2 = 42

Step-by-Step Solution

Step 1: Multiply the multiplicand by the last digit of the multiplier, 2: 21 × 2 = 42.

  • 1 × 2 = 2. Write 2.
  • 2 × 2 = 4. Write 4.

21 × 2

=

42

Check It, and What It Is Not

Check by dividing back. Multiplication and division undo each other, so 42 ÷ 2 = 21 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.

21 × 2 is a number, not an area. If those are the sides of a room in feet, the answer is 42 square feet — the same arithmetic, a different question, and it is answered by the square footage calculator.

Related Calculations

See Also

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 21 × 2? (The answer is: 42). Enter the multiplicand (e.g. '21') and the multiplier (e.g. '2') and hit the button. The order of the two numbers does not matter — 21 × 2 and 2 × 21 are the same product — so either number 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 21

MultiplicationProduct
11 × 222
12 × 224
13 × 226
14 × 228
15 × 230
16 × 232
17 × 234
18 × 236
19 × 238
20 × 240
21 × 242
22 × 244
23 × 246
24 × 248
25 × 250
26 × 252
27 × 254
28 × 256
29 × 258
30 × 260

FAQ

What is 21 × 2?

21 × 2 = 42

Is 21 × 2 the same as 2 × 21?

Yes. Multiplication is commutative, so both come to 42. Only the working differs: this page multiplies by 2, which gives a single partial product.

How do you check that 21 × 2 = 42?

Divide the product back by one of the factors: 42 ÷ 2 = 21 exactly, with no remainder. Multiplication and division undo each other, which is what makes this check work.

What are the partial products of 21 × 2?

There is only one: the multiplier 2 has a single digit, so 21 × 2 = 42 is written straight under the line, with no addition step.

See Also