Multiply 2-digit numbers with mental math - partial products (grade 4 math)

In this lesson we use mental math, specifically partial products, to multiply a two-digit number by a single-digit number. Partial products means we multiply numbers part-by-part. For example, 5 × 36 is done as 5 × 30 and 5 × 6, and those two parts are added. You can quite easily do these in your head when one number has two digits and the other has one.

This concept is very important, as it is the basis for the regular multi-digit multiplication algorithm studied in 4th grade.

See also

Another video on partial products — this one includes three-digit numbers and money amounts

Math Mammoth Multiplication 2 — a workbook with worksheets and lessons for long division, remainder, factors, and primes

Math Mammoth Grade 4 curriculum

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