>120
thì tính số số từ 1 đến 119 có bao nhiu số thì lấy: 119 -1+1 =119
rồi lấy 118 chia 2=59 cặp (tính thêm 60 nữa là 119)
rồi lấy tổng (119+1) + (118+2) +....+(59+61) +60
mỗi cặp đều có tổng là 120 thì lấy: 120.59+60=7140
OK
>120
thì tính số số từ 1 đến 119 có bao nhiu số thì lấy: 119 -1+1 =119
rồi lấy 118 chia 2=59 cặp (tính thêm 60 nữa là 119)
rồi lấy tổng (119+1) + (118+2) +....+(59+61) +60
mỗi cặp đều có tổng là 120 thì lấy: 120.59+60=7140
OK
the sum of all numbers that smaller than 120 is ....................
The sum of all natural numbers that are smaller than 500 and divisible by 5 is ............
The sum of all natural numbers that are smaller than 500 and divisible by 5 is ............
The sum of all natural numbers that are smaller than 500 and divisible by 5 í ......
the average of all even numbers that are smaller than 1000 is
the sum of two consecutive even numbers is 850. the smaller is ...
if the difference of two numbers is 12 and the sum of them is 32then the value of the smaller number is .....
The sum of two numbers is 90. The greater number is 2 times the smaller number. Find the greater number.
If the sum of two numbers is 3756 and their difference is 1864 then the smaller number is.....