Multiplication
Lessons in this chapter
About Multiplication
Multiplication in 4th grade moves beyond the tables into multi-digit methods, and adds a meaning of multiplication kids have not met before.
Interpret Multiplication as a Comparison and Multiply by Multiples of 10 introduces the comparison reading: “four times as many” is multiplication, even though nothing is being grouped. This is the meaning that word problems use most and that kids recognize least.
Multiply Numbers up to 4 Digits by a Single-Digit number builds the standard method, where each digit is multiplied in turn and the carries are tracked. Place value does the work here, which is why the number system chapter comes first.
Multiply 2-Digit Numbers by 2-Digit Numbers is the big step. Every digit in one number has to meet every digit in the other, which is four products to track and combine, and the shift of the second row one place left is the part kids drop.
Multiply Numbers up to 4 Digits by Single-Digit Numbers Mentally and Estimate Products closes the chapter with the sanity check. Rounding 47 × 62 to 50 × 60 gives 3,000, so an answer of 294 is visibly wrong.
Each of the four lessons opens as a 4th grade math worksheet in the page. Interpret Multiplication as a Comparison and Multiply by Multiples of 10, Multiply 2-Digit Numbers by 2-Digit Numbers and the estimation lesson each set math problems that are worked and scored as you answer them. All four are free to try, with no login needed for your first 3.
Frequently asked questions
Interpret Multiplication as a Comparison and Multiply by Multiples of 10 introduces the comparison reading, where four times as many is multiplication even though nothing is being grouped. Multiply Numbers up to 4 Digits by a Single-Digit number builds the standard method, Multiply 2-Digit Numbers by 2-Digit Numbers is the big step, and the chapter closes with mental multiplication and estimating products. The comparison work sits in Operations and Algebraic Thinking (4.OA) and the multi-digit methods in Number and Operations in Base Ten (4.NBT).
Phrases like “four times as many”. Nothing is being grouped, but it is still multiplication, and it is the form word problems use most often.
Remembering to shift the second row one place left. That shift is there because you are multiplying by tens, and dropping it is the most common error at this level.
Because it is the pattern the long method relies on. Once 6 × 40 is seen as 6 × 4 with a zero appended, the second row of a long multiplication makes sense.
Round both factors to easy numbers. 47 × 62 is roughly 50 × 60, so about 3,000, which catches an answer that is wildly out.
Completely. Every multi-digit method is built from single-digit facts, so a gap in the tables shows up as an error in every long multiplication.