18是倍数,6是约数. .
看图写算式. (1) + + = . × = (2) + = = . × = = (3) + + + = . × = .
+=+= .(判断对错)
﹣= 想: 个减去 个得 个,就是 .
﹣=﹣= .(判断对错)
“﹣”表示 个减去 个,还剩 个,即 .