63 = 7 x 9

Số  có 2006 chữ số 7 luôn chia hết cho 7

Để số có 2006 chữ số 7 chia hết cho 9 thì tổng các chữ số phải chia hết cho 9

Tổng các chữ số của số có 2006 chữ số 7 :

2006 x 7 = 14042

Số 14042 chia cho 9 dư 2

Nên phải cộng thêm số đó 7 đơn vị nữa thì số đó chia hết cho 63

Bằng 7 đúng 100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000%

Nếu 63 bị chia hết chỉ có thể chia cho chính nó,chính là 7=>9

=)) Ta sẽ thêm ít nhất 7 đơn vị

k cho mình nhé

Chia hết cho 63 thì chia hết cho 7 và chia hết cho 9 mà số có các chữ số 7 đều chia hết cho 7.

Ta thấy  2006 x 7 = 14042

Để 14042 chia hết cho 9 ta cần thêm vào 7 đơn vị để được 14049 chia hết cho 9.

Số này chia hết cho 7 nên thêm vào 7 đơn vị cũng chia hết cho 7.

Vậy để số này chia hết cho 63 cần thêm vào 7 đơn vị.

Cách 2 : 

Chia hết cho 63 thì chia hết cho 7 và chia hết cho 9.

Ta thấy  2006 : 9 = 222 (dư 8)

Hay còn lại 77777777 (8 chữ số 7) chia hết cho 7 và thêm 7 đơn vị nữa cũng chia hết cho 7 và chia hết cho 9.

Vậy để chia hết cho 63 cần thêm vào số này 7 đơn vị.

(Số này có dạng là 777...784 có 2004 chữ số 7)

vì 63=9*7 nên số đó phải chia hết cho 9 và 7

7*2006=14042 tổng các chữ số là 11 vậy cần ít nhất 7 đơn vị

thêm 7 đơn vị vì 7 chia hết ch 7

63 = 9 x 7 

Nên bắt buộc số đỏ phải chia hết cho 7 và 9 

Vì được viết bằng 2006 chữ số 7 nên số đó đã chia hết cho 7 

Nhưng 7 x 2006 = 14042 , tổng các chữ số là 11 , muốn chia hết cho 9 cần thêm 7 đơn vị .

7 cũng chia hết cho 7 nên thỏa mãn điều kiện .

Cần thêm ít nhất 7 đơn vị vào số đó để số đó chia hết cho 63

minh ko biet!

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

cần cộng thêm 7 đơn vị

cần cộng thêm 7 đơn vị nữa.

1 số được viết bằng 2006 chữ số 7 => số đó chia hết cho 7

Mà 7 và 9 là hai số nguyên tố cùng nhau nên số chia hết cho 7 và 9 sẽ chia hết cho 63

Tổng các chữ số là: 2006 x 7 = 14042 chia 9 dư 2

=> Cần thêm vào số đó 7 đơn vị để được số chia hết cho 7 và 9 <=> chia hết cho 63

bạn k mình câu trước luôn nha thank

2006 + 7 - 63=1950