Abstract: A teaching aid for teaching young children counting in the tens numbering systems, in which four side by side stacks of nine blocks are each slidable on respective rods held in a frame, each of the nine blocks having one face of each block in the stack imprinted in order with a cardinal number, the blocks in the second, third, and fourth stacks also marked respectively with one, two, and three zeros to the left of the cardinal number appearing thereon. Each of the cardinal numbers on the blocks in each stack are in distinct colors, the zeros color matched to the color of the cardinal number of the corresponding place on the adjacent stack. The blocks in each stack are progressively sized wider to the left in proportion to the number of number and zero digits imprinted thereon.