Long Multiplication: 90 × 15
What is 90 × 15?
Answer
90 × 15 and 15 × 90 are the same product — the order of the factors never changes the answer, only the working. Below, 90 is multiplied by 15 in a column, digit by digit.
90 × 15 in a Column
The multiplicand goes on top, the multiplier underneath, both aligned on the right. Each digit of the multiplier produces its own partial product, and the partial products are added up.
| 9 | 0 | |||
| × | 1 | 5 | ||
| 4 | 5 | 0 | ||
| + | 9 | 0 | 0 | |
| 1 | 3 | 5 | 0 |
Step-by-Step Solution
Step 1: Multiply the multiplicand by the last digit of the multiplier, 5: 90 × 5 = 450.
- 0 × 5 = 0. Write 0.
- 9 × 5 = 45. Write 5 and carry 4.
- No digits are left, so the carried 4 is written in front: the partial product is 450.
Step 2: The next digit of the multiplier is 1, and it stands for 10: 90 × 10 = 900.
- 0 × 1 = 0. Write 0.
- 9 × 1 = 9. Write 9.
450 + 900
=1,350
Adding the partial products finishes the work: 90 × 15 = 1,350.
Check It, and What It Is Not
Check by dividing back. Multiplication and division undo each other, so 1,350 ÷ 15 = 90 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.
90 × 15 is a number, not an area. If those are the sides of a room in feet, the answer is 1,350 square feet — the same arithmetic, a different question, and it is answered by the square footage calculator.
Related Calculations
See Also
- Long Division Calculator - Step-by-step long division with detailed explanation
- Multiplying Fractions Calculator - Multiply fractions, mixed numbers and whole numbers step by step
- Factors of a Number - List all Factors and Factor Pairs of a Number
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers
- Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
<a href="https://calculat.io/en/number/long-multiplication/90--15">90 × 15 = 1,350 - Long Multiplication - Calculatio</a>