Long Multiplication: 45 × 4
What is 45 × 4?
Answer
45 × 4 and 4 × 45 are the same product — the order of the factors never changes the answer, only the working. Below, 45 is multiplied by 4 in a column, digit by digit.
45 × 4 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.
| 4 | 5 | ||
| × | 4 | ||
| 1 | 8 | 0 |
Step-by-Step Solution
Step 1: Multiply the multiplicand by the last digit of the multiplier, 4: 45 × 4 = 180.
- 5 × 4 = 20. Write 0 and carry 2.
- 4 × 4 = 16, plus the carried 2 makes 18. Write 8 and carry 1.
- No digits are left, so the carried 1 is written in front: the partial product is 180.
45 × 4
=180
Check It, and What It Is Not
Check by dividing back. Multiplication and division undo each other, so 180 ÷ 4 = 45 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.
45 × 4 is a number, not an area. If those are the sides of a room in feet, the answer is 180 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/45--4">45 × 4 = 180 - Long Multiplication - Calculatio</a>