11. The reason why mental arithmetic is difficult has nothing to do with a limited brain capacity. 12. Currently, basic and advanced courses in abacus and mental arithmetic are available at private learning centres nationwide. 13. Apply an appropriate method for computing from among mental arithmetic , paper pencil computations, calculators, and computer models. 14. In grade schools, students are sometimes taught the method of complements as a shortcut useful in mental arithmetic . 15. While he examined my treasures _ polite or interested, I couldn't tell _ I did some mental arithmetic . 16. When Murray became the youngest millionaire in rodeo history at 23, a fellow rider did some mental arithmetic . 17. During Sunday's contest, each student took part in a 10-minute mental arithmetic test before the 20-minute sempoa contest. 18. Mental arithmetic was found to be ineffective by at least one study, especially in students counting backward by seven.19. Mental arithmetic was first introduced in Indonesia at the end of 1995 due to its popularity in the region.20. :So clearly, going to either extreme is bad-a happy medium for mental arithmetic is somewhere between 2 and 60.
