50

chiil

Cửa hàng đã bán số bóng đèn là:

       81 : 3 = 27(bóng đèn)

Cửa hàng còn lại số bóng đèn là:

     81 - 27 = 54(bóng đèn)

         Đáp số: 54 bóng đèn

Có ý kiến : 

đề thiếu 

@Trunglaai?

Số số hạng của dãy số là:

10-0+1=11(số)

Tổng của dãy số là: \(\left(10+0\right)\times\frac{11}{2}=10\times\frac{11}{2}=5\times11=55\)

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5 chiếc bút chì dài số cm là

9 x 5 = 45 (cm)

vậy : .....

Năm chiếc bút chì dài giống nhau có tổng độ dài là:

9×5=45(cm)

Đáp số :45cm

99 : 9 = 11

\(99\div9=11\)

\(55+45-90+1=100-91=9\)

Ai k tôi k lại

55 + 45 - 90 + 1

= 100 - 90 + 1

= 10 + 1

= 11

100 viên bi

100 viên

=35 nha

Bài giải đâu vậy ?