... 10, you can multiply any two 1-digit numbers together The next step is to multiply 2- and 3-digit numbers by 1-digit numbers As we’ll see, these 2-by-1s and 3-by-1s are the essential building ... boost your memory Once you’ve mastered 2-by-1 and 3-by-1 multiplication, you can actually most 2-by-2 multiplication problems, using the factoring method Most 2-digit numbers can be factored into ... Power Kelly, Short-Cut Math Problems Because 2-by-1 and 3-by-1 multiplication problems are so important, an ample number of practice problems are provided Calculate the following 2-by-1 multiplication...