1975-1978; Soroban, Japanese abacus with coloured plastic beads in cardboard case. The soroban has 1 bead above the bar and 4 beads below. It is used for calculations in base 10. The soroban was developed from the Chinese abacus which had 2 beads above the bar and 5 below for working in base 16. 1978-112; Science Museum/Science & Society Picture Library > Science & Technology > Mathematics Soroban, Japanese, 1975-1978.; http://www.ingenious.org.uk/media/4.0_SAC/webimages/1032/5/10325642_2.jpg World > Asia > Japan