I'm sure throughout your child's life, you remember a point at which they were learning about Lowest Common Multiples (LCM's), or as they're known when studying fractions, Lowest Common Denominators (LCD's). Although they are possible to figure out in one's head, very slowly, you can also figure them out using a multiplication chart.
So, as one of my students and I were recently printing out a new copy of a 30 x 30 multiplication chart, we discovered this gem........... yes, it really is...... a LCM/CLD CHART!!
Although I couldn't find who actually made it up, and I couldn't find the original place on the website where this lovely chart was posted, I am thoroughly thankful for it, and have linked the address where I found it (thanks to a Google Image search).
Also, in case you're wondering, there is a great set of multiplication charts that I use and will include them below (click on the image for the link to the image, or the website where possible).
In a class where students are not allowed calculators, multiplication tables are generally allowed. So far, students of mine from grade 6 up have been allowed to use them in the classroom, so they might be worthwhile printing out for you too! They also look pretty snazzy in a sheet protector as well (kids enjoy using their pencils to follow the lines to the product).