求數(shù)(三年級奧數(shù)題及答案)

字號:

求數(shù)
    (1)4×4× …… ×4(25個4)積的個位數(shù)是幾?
    (2)20個2相乘,積末尾數(shù)字是幾?
    點擊下一頁查看答案
    解答:(1)按照乘數(shù)的個數(shù),積的末位數(shù)字的規(guī)律是:4,6,4,6,4,6,……奇數(shù)個4相乘得數(shù)的末尾數(shù)字是4,偶數(shù)個4相乘得數(shù)的末尾數(shù)是6,25是奇數(shù),25個4相乘,積的末尾數(shù)字是4.
    (2)按照乘數(shù)的個數(shù),末尾數(shù)字的規(guī)律是2,4,8,6,2,4,8,6……4個一組20÷4=5所以20個2相乘,積末尾數(shù)字是6.