Abstract: A tool, for teaching and learning multiplication includes two strips. The first strip has numbers set down in sequence from left to right in order of increasing value with each subsequent number increasing in value by adding the first number to the immediately preceding number in the sequence. The second strip is a filter, which when overlain on the first strip blocks out a repeating fixed quantity of the numbers to leave a visible second sequence such that any visible number in the visible second sequence is a fixed number additive to an immediately preceding blocked-out number. This arrangement means that any selected number in the visible second sequence is the product of the filter number times a counted position from the left of the selected number. The tool is preferably assembled so that there are numerous strips in a set that have a pivotal connection.