Multiplying three-digit numbers
Multiplying three-digit numbers by a single digit is a Grade 4 skill in Saxon Math Intermediate 4 (Chapter 6). Work right to left: multiply ones, then tens, then hundreds, carrying over any two-digit products. For 275 x 4: ones 4x5=20 (write 0 carry 2), tens 4x7=28 plus 2 = 30 (write 0 carry 3), hundreds 4x2=8 plus 3 = 11. Answer: 1100. The most critical error is forgetting to add the carried digit after each multiplication step.
Key Concepts
Property To multiply a three digit number, you multiply in order, from right to left. First multiply the ones digit, then the tens digit, and finally the hundreds digit. If a product in any column is a two digit number, you write the ones digit down and carry the tens digit over to the next column on the left.
Example Example 1: To solve $234 \times 3$, first multiply $3 \times 4 = 12$. Write down 2, carry over 1. Then, $3 \times 3 = 9$, plus the carried 1 is 10. Write down 0, carry over 1. Finally, $3 \times 2 = 6$, plus the carried 1 is 7. The answer is $702$. Example 2: For $768 \times 3$, start with $3 \times 8 = 24$. Write 4, carry 2. Next, $3 \times 6 = 18$, plus 2 is 20. Write 0, carry 2. Lastly, $3 \times 7 = 21$, plus 2 is 23. The final product is $2304$.
Explanation Think of it like stacking blocks, starting from the right! You handle the ones first, then the tens, then the hundreds. If a stack gets too high (more than 9), you just carry the extra bundle of ten over to the next stack. This keeps everything organized and leads you to the correct grand total.
Common Questions
How do you multiply 275 x 4?
Ones: 4x5=20, write 0 carry 2. Tens: 4x7=28, add 2=30, write 0 carry 3. Hundreds: 4x2=8, add 3=11, write 11. Answer: 1100.
How do you multiply 234 x 3?
Ones: 3x4=12, write 2 carry 1. Tens: 3x3=9, add 1=10, write 0 carry 1. Hundreds: 3x2=6, add 1=7. Answer: 702.
How do you multiply 768 x 3?
Ones: 3x8=24, write 4 carry 2. Tens: 3x6=18, add 2=20, write 0 carry 2. Hundreds: 3x7=21, add 2=23. Answer: 2304.
What is the most common error when multiplying three-digit numbers?
Forgetting to add the carried digit. After multiplying each place, always check the top of the next column for a carried number before writing your digit.
What is the basic process for multiplying any multi-digit number?
Always work right to left (ones, tens, hundreds). Multiply each digit by the multiplier. If the product exceeds 9, write the ones digit and carry the tens digit to the next column.