1. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) Using Your Abacards ® Abacus is not need for this advanced activity! Click your or arrow keys to move the card ahead! For your IPAD swipe the screen. After each click say what you saw. Practice saying what you will see before you click! After using the Abacards ®, make up problems. Forward Backward

2. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 95x99= ? = 9,500-95 = 9,500-100+5 = 9,400+5 = 9,405 Mental math is Fun! Abacard®

3. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 42x99= ? = 4,200-42 = 4,200-100+58 = 4,100+58 = 4,158 Mental math is Fun! Abacard®

4. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 56x99= ? = 5,600-56 = 5,600-100+44 = 5,500+44 = 5,544 Mental math is Fun! Abacard®

5. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 28x99= ? = 2,800-28 = 2,800-100+72 = 2,700+72 = 2,772 Mental math is Fun! Abacard®

6. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 158x99= ? = 15,800-158 = 15,800-200+42 = 15,600+42 = 15,642 Mental math is Fun! Abacard®

7. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 129x99= ? = 12,900-129 = 12,900-200+71 = 12,700+71 = 12,771 Mental math is Fun! Abacard®

8. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 111x99= ? = 11,100-111 = 11,100-100-11 = 11,000-11 = 10,989 Mental math is Fun! Abacard®

9. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 144x99= ? = 14,400-144 = 14,400-200+56 = 14,200+56 = 14,256 Mental math is Fun! Abacard®

10. Rule: 99 x (a number) = 100 x (a number) -1 x (a number) 135x99= ? = 13,500-135 = 13,500-200+65 = 13,300+65 = 13,365 Mental math is Fun! Abacard®