TIMO Khối 5 – Vòng Quốc gia (Heat Round) – Đề số 2

Find the 2-digit number CA, given that A and C are two non-zero digits and the 2-digit numbers formed by these two digits have the following properties: 1. CA is divisible by 13; 2. AC is a square number;

Non-zero: Khác không; Digit: Chữ số; 2-digit number: Số có 2 chữ số; Property: Tính chất;

Divisible: Chia hết; Square number: Số chính phương.

5 numbers, A, B, C, D and E, represent different numbers from 1 to 9. Given the following conditions: 1. The sum of A and E is less than the sum of C and 5. 2. The sum of A, C and E equals D. 3. The sum of A and D equals B. 4. D is divisible by C. 5. The sum of A and C is less than E. 6. D is greater than 6. Find the number to represent D.

Different: Khác nhau; Condition: Điều kiện; Sum: Tổng; Less than: Bé hơn; Equal: Bằng;

Divisible: Chia hết; Greater than: Lớn hơn.

A stationery store had a batch of ball pens. One half but 6 fewer pens were sold on the first day. One half of the remaining part and 8 more pens were sold on the second day. Finally, 20 ball pens are left. How many ball pen(s) did the stationery store have originally?

Half: Một nửa; Remaining: Phần còn lại; Left: Còn lại; Originally: Ban đầu.