You can simplify the display code a little more:
// --- minutes ones
digitalWrite( 1, (minute%10) & 0b00000001); // 1's
digitalWrite( 2, (minute%10) & 0b00000010); // 2's
digitalWrite( 3, (minute%10) & 0b00000100); // 4's
digitalWrite( 4, (minute%10) & 0b00001000); // 8's
// --- minutes tens
digitalWrite( 5, (minute/10) & 0b00000001); // 1's
digitalWrite( 6, (minute/10) & 0b00000010); // 2's
digitalWrite( 7, (minute/10) & 0b00000100); // 4's
// --- hours ones
digitalWrite( 8, (hour%10) & 0b00000001); // 1's
digitalWrite( 9, (hour%10) & 0b00000010)); // 2's
digitalWrite(10, (hour%10) & 0b00000100); // 4's
digitalWrite(11, (hour%10) & 0b00001000); // 8's
// --- hours tens
digitalWrite(12, (hour/10) & 0b00000001); // 1's
digitalWrite(13, (hour/10) & 0b00000010); // 2's
Other suggestions to the code if you don't mind them at this stage of your project.
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