2.2 Multiply by Two Digit Numbers

Front

What is multiplication?

Back

Multiplication is a mathematical operation that represents the repeated addition of a number. For example, 4 multiplied by 3 (4 x 3) means adding 4 three times (4 + 4 + 4) which equals 12.

Front

What does it mean to multiply by a two-digit number?

Back

Multiplying by a two-digit number involves multiplying a number by a number that has two digits, such as 12, 25, or 34. This often requires breaking the two-digit number into tens and ones.

Front

How do you estimate the product of two numbers?

Back

To estimate the product, round each number to the nearest ten or hundred, then multiply the rounded numbers. This gives a quick approximation of the actual product.

Front

What is the product of 18 and 22?

Back

396

Front

How do you multiply a two-digit number by a one-digit number?

Back

Multiply the one-digit number by each digit of the two-digit number, starting from the right. Then, add the results together.

Front

What is the area of a rectangle?

Back

The area of a rectangle is found by multiplying its length by its width. For example, if a rectangle is 5 units long and 3 units wide, its area is 5 x 3 = 15 square units.

Front

How many pounds of food does a lion need in one year if it needs 15 pounds a day?

Back

A lion needs 5,460 pounds of food in one year (15 pounds/day x 365 days).

Front

What is a multi-step problem?

Back

A multi-step problem requires more than one operation to solve. For example, first you might need to multiply, then add or subtract to find the final answer.

Front

How do you find the total number of plants in rows?

Back

To find the total number of plants, multiply the number of rows by the number of plants in each row. For example, 27 rows of 14 plants each equals 378 plants.

Front

What is the best estimate for the number of bricks in a wall that is 23 bricks wide and 130 bricks high?

Back

The best estimate is about 2,000 bricks (23 x 130 = 2,990, rounded to 2,000).