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We call a number odd looking if all of its digits are odd. How many three-digit odd-looking numbers are there?

 Nov 19, 2020
 #1
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(111, 113, 115, 117, 119, 131, 133, 135, 137, 139, 151, 153, 155, 157, 159, 171, 173, 175, 177, 179, 191, 193, 195, 197, 199, 311, 313, 315, 317, 319, 331, 333, 335, 337, 339, 351, 353, 355, 357, 359, 371, 373, 375, 377, 379, 391, 393, 395, 397, 399, 511, 513, 515, 517, 519, 531, 533, 535, 537, 539, 551, 553, 555, 557, 559, 571, 573, 575, 577, 579, 591, 593, 595, 597, 599, 711, 713, 715, 717, 719, 731, 733, 735, 737, 739, 751, 753, 755, 757, 759, 771, 773, 775, 777, 779, 791, 793, 795, 797, 799, 911, 913, 915, 917, 919, 931, 933, 935, 937, 939, 951, 953, 955, 957, 959, 971, 973, 975, 977, 979, 991, 993, 995, 997, 999) = 125 such numbers.

 Nov 19, 2020
 #2
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Thx, guest....a faster way

 

5  integers  in  each  of the hundreds, tens and ones place are odd.....

 

So  5 * 5 * 5   =   125

 

cool cool cool

 Nov 19, 2020

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