... 21 4) Q = + 62 + 63 + + 69 9 chia hết cho 43 ( ) ( ) ( Q = + 62 + 63 + 64 + 65 + 66 + + 69 7 + 69 8 + 69 9 ( ) ( ) ( Q= + + 62 + 64 + + 62 + + 69 7 + + 62 ) ) Q= 6. 43 + 64 .43 + + 69 7. 43 ⇒ Q ... 393 − 3 97 =−4 + ( −4 ) + + ( −4 ) ( Có 50 số -4 ) = −4.50 = −200 11) 121.33 + 65 .33 + 1 86. 67 = 33.(121 + 65 ) + 1 86. 67 = 33.1 86 + 1 86. 67 = 1 86. (33 + 67 ) = 1 86. 100 = 1 860 0 12) ( −1 26 ) + 64 + (... 63 + 64 + + 62 019 + 62 020 ) N = (1 + ) + 63 (1 + ) + + 62 019 (1 + ) N = 6. 7 + 63 .7 + + 62 019 .7 ⇒ N + N = + 62 + 63 + + 62 020 ( ) N= + + 62 + + 62 019 K K =1 + + 62 + + 62 019