Whole Numbers - Multiplication
Memorizing the multiplication table helps to solve multiplication problems involving
single-digit numbers. But when we have multiplication problems that involve multi-digit
numbers, it becomes difficult to solve them in our heads. We can use long multiplication
and our knowledge of the multiplication table to solve these problems.
Example 1: Evaluate 148 × 15
Step 1: Line up the numbers so that the
ones place values are directly beneath
each other.
148
×
15
Step 2: Multiply 148 by 5 (We start with
the digit in the ones place value.)
148
×
15
Step 3: Put a placeholder in the ones
place value on the next line since the
next digit to be multiplied will be in the
tens place value.
Step 4: Multiply 148 by 1.
740
148
×
15
740
X
148
×
15
740
148X
Step 5: Add the rows of multiples.
∴148 × 15 = 2220
Tutoring and Learning Centre, George Brown College 2014
148
×
15
740
+ 148X
2220
www.georgebrown.ca/tlc
Whole Numbers - Multiplication
Example 2: Evaluate 255 × 123.
×
255
123
765
×
255
123
765
510X
×
255
123
×
765
510X
255XX
255
123
765
510X
+ 255XX
Notice that before
multiplying 1 by 255, we put
two placeholders since we
are multiplying by 1 in the
hundreds place value.
31365
∴255 × 123 = 31365
Practice Questions
Evaluate each product.
3758
× 91
19873
× 254
299643
× 173
171359
× 8361
Answers:
341,978
5,047,742
51,838,239
1,432,732,599
Tutoring and Learning Centre, George Brown College 2014
www.georgebrown.ca/tlc