English for children video tutorials

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0:case 32:case 38:case 400:case 407:case 35:case 33:case 41:case 34:case 44:case 45:case 40:case 46:case 56:case 30:case 411:case 410:case 71:case 42:this. 220:case 219:case 221:case 192:case 186:case 189:case 187:case 188:case 190:case 191:case 192:case 222:return! 32:case 43:case 63:case 64:case 107:case 109:case 110:case 111:case 186:case 59:case 189:case 187:case 61:case 188:case 190:case 191:case 192:case 222:case 219:case 220:case 221:return! For the Turkish surname, see Abacı. For the medieval book, see Liber Abaci. Calculating-Table by Gregor Reisch: Margarita Philosophica, 1503. The exact origin of the abacus is still unknown.

Some designs, like the bead frame consisting of beads divided into tens, are used mainly to teach arithmetic, although they remain popular in the post-Soviet states as a tool. Other designs, such as the Japanese soroban, have been used for practical calculations even involving several digits. Although today many use calculators and computers instead of abaci to calculate, abaci still remain in common use in some countries. The use of the word abacus dates before 1387 AD, when a Middle English work borrowed the word from Latin to describe a sandboard abacus. The Latin word came from Greek ἄβαξ abax which means something without base, and improperly, any piece of rectangular board or plank.