三年級口算：整十數(shù)乘整十數(shù)

口算題：整十數(shù)乘整十數(shù)
    （1）70 × 40 =
    （2）30 × 10 =
    （3）30 × 10 =
    （4）40 × 20 =
    （5）60 × 50 =
    （6）10 × 30 =
    （7）20 × 70 =
    （8）80 × 50 =
    （9）30 × 70 =
    （10）30 × 30 =
    （11）40 × 60 =
    （12）60 × 50 =
    （13）70 × 80 =
    （14）50 × 50 =
    （15）90 × 60 =