Multiply a 3-digit number by a 1-digit number

Multiplication of a three-digit whole number (100–999) by a one-digit whole number (0–9) is understood through place value: the one-digit factor multiplies the hundreds, tens, and ones, or the number’s expanded form, and the resulting partial products are combined with regrouping when needed. Area models and the standard written algorithm represent this same decomposition, including numbers with zero digits; the scope does not extend to multiplying two multi-digit factors or more advanced generalizations.

Detailed Explanation: Multiply a 3-digit number by a 1-digit number

To multiply a 3-digit number by a 1-digit number, multiply from the ones place to the tens place to the hundreds place. Regroup when a product is $10$ or more.

Example: Find $326 \times 4$ .

Multiply the ones:
$4 \times 6 = 24$ .
Write $4$ in the ones place and regroup $2$ tens.
Multiply the tens:
$4 \times 2 = 8$ tens. Add the $2$ regrouped tens:
$8 + 2 = 10$ tens.
Write $0$ in the tens place and regroup $1$ hundred.
Multiply the hundreds:
$4 \times 3 = 12$ hundreds. Add the $1$ regrouped hundred:
$12 + 1 = 13$ hundreds.

So,

\begin{array}{r} \ \ 326\\ \times\ \ 4\\ \hline 1304 \end{array}

Therefore,

326 \times 4 = 1{,}304.

This also matches the place-value breakdown:

326 \times 4=(300\times4)+(20\times4)+(6\times4) =1200+80+24=1304.

Learn by doing: Multiply a 3-digit number by a 1-digit number

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Multiplication - Whole Number 3 x 1

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Multiply a 3-digit number by a 1-digit number

Detailed Explanation: Multiply a 3-digit number by a 1-digit number

Learn by doing: Multiply a 3-digit number by a 1-digit number

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Multiplication - Whole Number 3 x 1