D\u00e0n \u0111\u1ec1 t\u1ed5ng ch\u1eb5n v\u00e0 t\u1ed5ng l\u1ebb l\u00e0 2 b\u1ed9 s\u1ed1 quen thu\u1ed9c c\u1ee7a nhi\u1ec1u b\u1ea1n ch\u01a1i l\u00f4 \u0111\u1ec1. Hai d\u00e0n \u0111\u1ec1 n\u00e0y l\u00e0 g\u00ec, c\u00f3 bao nhi\u00eau con v\u00e0 g\u1ed3m nh\u1eefng con n\u00e0o. \u0110\u00e2y ch\u00ednh l\u00e0 l\u00e0 n\u1ed9i dung b\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y, m\u1eddi c\u00e1c b\u1ea1n t\u00ecm hi\u1ec3u.<\/p>\n
D\u00c0N \u0110\u1ec0 T\u1ed4NG CH\u1eb4N<\/strong><\/h2>\nD\u00c0N \u0110\u1ec0 T\u1ed4NG CH\u1eb4N L\u00c0 G\u00cc<\/strong><\/h3>\nD\u00e0n \u0111\u1ec3 t\u1ed5ng ch\u1eb5n l\u00e0 m\u1ed9t t\u1ed5ng \u0111\u1ec1 th\u01b0\u1eddng d\u00f9ng. D\u00e0n \u0111\u1ec1 n\u00e0y g\u1ed3m nh\u1eefng s\u1ed1 c\u00f3 t\u1ed5ng 2 ch\u1eef s\u1ed1 l\u00e0 s\u1ed1 ch\u1eb5n. C\u00e1c b\u1ea1n c\u0169ng \u0111\u00e3 bi\u1ebft t\u1ed5ng 2 l\u00e0 s\u1ed1 ch\u1eb5n khi m\u00e0 2 s\u1ed1 c\u00f9ng l\u00e0 s\u1ed1 l\u1ebb ho\u1eb7c 2 s\u1ed1 c\u00f9ng l\u00e0 s\u1ed1 ch\u1eb5n.<\/p>\n
V\u00ed d\u1ee5:<\/strong><\/em><\/p>\nS\u1ed1 3 v\u00e0 s\u1ed1 5 l\u00e0 s\u1ed1 l\u1ebb n\u00ean t\u1ed5ng c\u1ee7a 2 s\u1ed1 b\u1eb1ng 8 l\u00e0 s\u1ed1 ch\u1eb5n<\/em><\/p>\nS\u1ed1 4 v\u00e0 s\u1ed1 8 l\u00e0 s\u1ed1 ch\u1eb5n n\u00ean t\u1ed5ng c\u1ee7a 2 b\u1eb1ng 12 l\u00e0 s\u1ed1 ch\u1eb5n<\/em><\/p>\nD\u00c0N \u0110\u1ec0 N\u00c0Y G\u1ed2M NH\u1eeeNG CON N\u00c0O<\/strong><\/h3>\nNh\u01b0 \u0111\u00e3 n\u00f3i \u1edf ph\u1ea7n tr\u00ean. D\u00e0n \u0111\u1ec1 t\u1ed5ng ch\u1eb5n l\u00e0 b\u1ed9 s\u1ed1 c\u00f3 2 ch\u1eef s\u1ed1 l\u00e0 s\u1ed1 ch\u1eb5n ho\u1eb7c 2 s\u1ed1 l\u00e0 s\u1ed1 l\u1ebb. V\u00ec v\u1eady n\u00f3 g\u1ed3m nh\u1eefng s\u1ed1 c\u1ee7a 2 d\u00e0n \u0111\u1ec1 ch\u1eb5n ch\u1eb5n v\u00e0 d\u00e0n \u0111\u1ec1 l\u1ebb l\u1ebb.<\/p>\n
Nh\u01b0 v\u1eady n\u00f3 c\u00f3 50 s\u1ed1 v\u00e0 g\u1ed3m nh\u1eefng s\u1ed1 sau:<\/p>\n
11, 13, 15, 17, 19, 31, 33, 35, 37, 39, 51, 53, 55, 57, 59, 71, 73, 75, 77, 79, 91, 93, 95, 97, 99<\/p>\n
00, 02, 04, 06, 08, 20, 22, 24, 26, 28, 40, 42, 44, 46, 48, 60, 62, 64, 66, 68, 80, 82, 84, 86, 88<\/p>\n
D\u00c0N \u0110\u1ec0 T\u1ed4NG L\u1eba<\/strong><\/h2>\nD\u00c0N \u0110\u1ec0 T\u1ed4NG L\u1eba L\u00c0 G\u00cc<\/strong><\/h3>\nT\u01b0\u01a1ng t\u1ef1 nh\u01b0 d\u00e0n \u0111\u1ec1 t\u1ed5ng ch\u1eb5n. T\u1ed5ng l\u1ebb l\u00e0 b\u1ed9 s\u1ed1 c\u00f3 t\u1ed5ng 2 ch\u1eef s\u1ed1 kh\u00f4ng chia h\u1ebft cho 2. Trong to\u00e1n h\u1ecdc th\u00ec t\u1ed5ng c\u1ee7a 2 s\u1ed1 l\u00e0 s\u1ed1 l\u1ebb khi 2 s\u1ed1 \u0111\u00f3 l\u00e0 1 s\u1ed1 ch\u1eb5n v\u00e0 1 s\u1ed1 l\u1ebb.<\/p>\n<\/figure>\nV\u00ed d\u1ee5: <\/em><\/strong><\/p>\nS\u1ed1 7 v\u00e0 s\u1ed1 8 l\u00e0 c\u00f3 t\u1ed5ng 2 s\u1ed1 b\u1eb1ng 15 l\u00e0 s\u1ed1 l\u1ebb<\/em><\/p>\nS\u1ed1 2 v\u00e0 s\u1ed1 9 c\u00f3 t\u1ed5ng 2 s\u1ed1 l\u00e0 11 l\u00e0 s\u1ed1 l\u1ebb<\/em><\/p>\nD\u00c0N \u0110\u1ec0 N\u00c0Y G\u1ed2M NH\u1eeeNG CON N\u00c0O<\/strong><\/h3>\nNg\u01b0\u1ee3c l\u1ea1i v\u1edbi t\u1ed5ng ch\u1eb5n. D\u00e0n \u0111\u1ec1 t\u1ed5ng l\u1ebb bao g\u1ed3m c\u00e1c s\u1ed1 \u0111\u1ec1 c\u1ee7a 2 b\u1ed9 s\u1ed1 ch\u1eb5n l\u1ebb v\u00e0 l\u1ebb ch\u1eb5n. D\u00e0n \u0111\u1ec1 n\u00e0y g\u1ed3m 50 s\u1ed1 sau:<\/p>\n
01, 03, 05, 07, 09, 21, 23, 25, 27, 29, 41, 43, 45, 47, 49, 61, 63, 65, 67, 69, 81, 83, 85, 87, 89<\/p>\n
10, 12, 14, 16, 18, 30, 32, 34, 36, 38, 50, 52, 54, 56, 58, 70, 72, 74, 76, 78, 90, 92, 94, 96, 98<\/p>\n
Tr\u00ean \u0111\u00e2y l\u00e0 to\u00e0n b\u1ed9 ki\u1ebfn th\u1ee9c v\u1ec1 2 d\u00e0n \u0111\u1ec1 c\u1ee7a ch\u00fang ta. Ch\u00fac c\u00e1c b\u1ea1n \u00e1p d\u1ee5ng th\u00e0nh c\u00f4ng v\u00e0o th\u1ef1c t\u1ebf ch\u01a1i l\u00f4 \u0111\u1ec1.<\/p>\n<\/div>\n<\/div>\n
chuy\u00ean gia soi c\u1ea7u mi\u1ec1n b\u1eafc cao c\u1ea5p.<\/span><\/strong><\/h4>\n
D\u00e0n \u0111\u1ec3 t\u1ed5ng ch\u1eb5n l\u00e0 m\u1ed9t t\u1ed5ng \u0111\u1ec1 th\u01b0\u1eddng d\u00f9ng. D\u00e0n \u0111\u1ec1 n\u00e0y g\u1ed3m nh\u1eefng s\u1ed1 c\u00f3 t\u1ed5ng 2 ch\u1eef s\u1ed1 l\u00e0 s\u1ed1 ch\u1eb5n. C\u00e1c b\u1ea1n c\u0169ng \u0111\u00e3 bi\u1ebft t\u1ed5ng 2 l\u00e0 s\u1ed1 ch\u1eb5n khi m\u00e0 2 s\u1ed1 c\u00f9ng l\u00e0 s\u1ed1 l\u1ebb ho\u1eb7c 2 s\u1ed1 c\u00f9ng l\u00e0 s\u1ed1 ch\u1eb5n.<\/p>\n
V\u00ed d\u1ee5:<\/strong><\/em><\/p>\n S\u1ed1 3 v\u00e0 s\u1ed1 5 l\u00e0 s\u1ed1 l\u1ebb n\u00ean t\u1ed5ng c\u1ee7a 2 s\u1ed1 b\u1eb1ng 8 l\u00e0 s\u1ed1 ch\u1eb5n<\/em><\/p>\n S\u1ed1 4 v\u00e0 s\u1ed1 8 l\u00e0 s\u1ed1 ch\u1eb5n n\u00ean t\u1ed5ng c\u1ee7a 2 b\u1eb1ng 12 l\u00e0 s\u1ed1 ch\u1eb5n<\/em><\/p>\n Nh\u01b0 \u0111\u00e3 n\u00f3i \u1edf ph\u1ea7n tr\u00ean. D\u00e0n \u0111\u1ec1 t\u1ed5ng ch\u1eb5n l\u00e0 b\u1ed9 s\u1ed1 c\u00f3 2 ch\u1eef s\u1ed1 l\u00e0 s\u1ed1 ch\u1eb5n ho\u1eb7c 2 s\u1ed1 l\u00e0 s\u1ed1 l\u1ebb. V\u00ec v\u1eady n\u00f3 g\u1ed3m nh\u1eefng s\u1ed1 c\u1ee7a 2 d\u00e0n \u0111\u1ec1 ch\u1eb5n ch\u1eb5n v\u00e0 d\u00e0n \u0111\u1ec1 l\u1ebb l\u1ebb.<\/p>\n Nh\u01b0 v\u1eady n\u00f3 c\u00f3 50 s\u1ed1 v\u00e0 g\u1ed3m nh\u1eefng s\u1ed1 sau:<\/p>\n 11, 13, 15, 17, 19, 31, 33, 35, 37, 39, 51, 53, 55, 57, 59, 71, 73, 75, 77, 79, 91, 93, 95, 97, 99<\/p>\n 00, 02, 04, 06, 08, 20, 22, 24, 26, 28, 40, 42, 44, 46, 48, 60, 62, 64, 66, 68, 80, 82, 84, 86, 88<\/p>\n T\u01b0\u01a1ng t\u1ef1 nh\u01b0 d\u00e0n \u0111\u1ec1 t\u1ed5ng ch\u1eb5n. T\u1ed5ng l\u1ebb l\u00e0 b\u1ed9 s\u1ed1 c\u00f3 t\u1ed5ng 2 ch\u1eef s\u1ed1 kh\u00f4ng chia h\u1ebft cho 2. Trong to\u00e1n h\u1ecdc th\u00ec t\u1ed5ng c\u1ee7a 2 s\u1ed1 l\u00e0 s\u1ed1 l\u1ebb khi 2 s\u1ed1 \u0111\u00f3 l\u00e0 1 s\u1ed1 ch\u1eb5n v\u00e0 1 s\u1ed1 l\u1ebb.<\/p>\n V\u00ed d\u1ee5: <\/em><\/strong><\/p>\n S\u1ed1 7 v\u00e0 s\u1ed1 8 l\u00e0 c\u00f3 t\u1ed5ng 2 s\u1ed1 b\u1eb1ng 15 l\u00e0 s\u1ed1 l\u1ebb<\/em><\/p>\n S\u1ed1 2 v\u00e0 s\u1ed1 9 c\u00f3 t\u1ed5ng 2 s\u1ed1 l\u00e0 11 l\u00e0 s\u1ed1 l\u1ebb<\/em><\/p>\n Ng\u01b0\u1ee3c l\u1ea1i v\u1edbi t\u1ed5ng ch\u1eb5n. D\u00e0n \u0111\u1ec1 t\u1ed5ng l\u1ebb bao g\u1ed3m c\u00e1c s\u1ed1 \u0111\u1ec1 c\u1ee7a 2 b\u1ed9 s\u1ed1 ch\u1eb5n l\u1ebb v\u00e0 l\u1ebb ch\u1eb5n. D\u00e0n \u0111\u1ec1 n\u00e0y g\u1ed3m 50 s\u1ed1 sau:<\/p>\n 01, 03, 05, 07, 09, 21, 23, 25, 27, 29, 41, 43, 45, 47, 49, 61, 63, 65, 67, 69, 81, 83, 85, 87, 89<\/p>\n 10, 12, 14, 16, 18, 30, 32, 34, 36, 38, 50, 52, 54, 56, 58, 70, 72, 74, 76, 78, 90, 92, 94, 96, 98<\/p>\n Tr\u00ean \u0111\u00e2y l\u00e0 to\u00e0n b\u1ed9 ki\u1ebfn th\u1ee9c v\u1ec1 2 d\u00e0n \u0111\u1ec1 c\u1ee7a ch\u00fang ta. Ch\u00fac c\u00e1c b\u1ea1n \u00e1p d\u1ee5ng th\u00e0nh c\u00f4ng v\u00e0o th\u1ef1c t\u1ebf ch\u01a1i l\u00f4 \u0111\u1ec1.<\/p>\n<\/div>\n<\/div>\nD\u00c0N \u0110\u1ec0 N\u00c0Y G\u1ed2M NH\u1eeeNG CON N\u00c0O<\/strong><\/h3>\n
D\u00c0N \u0110\u1ec0 T\u1ed4NG L\u1eba<\/strong><\/h2>\n
D\u00c0N \u0110\u1ec0 T\u1ed4NG L\u1eba L\u00c0 G\u00cc<\/strong><\/h3>\n
D\u00c0N \u0110\u1ec0 N\u00c0Y G\u1ed2M NH\u1eeeNG CON N\u00c0O<\/strong><\/h3>\n
chuy\u00ean gia soi c\u1ea7u mi\u1ec1n b\u1eafc cao c\u1ea5p.<\/span><\/strong><\/h4>\n