Tinh nhanh 

9/15 cong 16/20 cong 25/25 cong 30/36 cong 49/35 cong 64/40 cong 81/45 cong 100/50

tinh tong cac so chia het cho 4

tinh nhanh

3 cong 8 cong 13 cong ...cong 48

1 cong 3 cong 5 cong 7 cong ...2021

TIM MOT SO CO 2 CHU SO , BIET RANG NEU SO DO CONG VOI 35 ROI CONG TIEP VOI 65 THI DUOC MOT SO MOI CO TONG CAC CHU SO BANG 18

tim mot so co hai chu so biet rang neu lay so do cong voi 35 roi cong tiep 65 thi duoc mot so moi co tong cac chu so la18.

1 , tinh bang cach tien nhat 

[500 cong 115 ] nhan 55 cong[ 600 cong 15 ] nhan 15 cong [ 700 - 85] nhan 85 cong [ 900 -285 ] nhan 45

giai tung buoc cho minh nha

tim mot so co hai chu so biet rang neu so do cong voi 35 roi cong tiep voi 65 thi duoc mot so moi cotong cac chu so bang 18?

tim so co 2 chu so biet rang cong so do voi 46 roi cong 54 thi duoc 1 so co tong cac chu so bang 18

tim so trung binh cong cac so 4;6'8'10;12;14;16;18. em cocach nao tinh nhanh so trung binh cong cua cac so tren khong

Trung binh cong cua n so la 80,biet mot trong cac so do la 100.Neu bo so 100 thi trung binh cong cac so con lai la 78. Tim n ?