int pins1[8] = {2,3,4,5,6,7,8}; // array of led pins for digit #1
int pins2[8] = {9,10,11,12,13,A0,A1,A5}; // array of led pins for digit #2

// Below is a 2D array of appropriate LEDs for each digit.
// You should set these to correspond to each segment of the display
// In this example the digits are set like this (where "#" is a segment):
//     2
//     #
//  7#   #3 
//     #<------8
//  6#   #4
//     # 
//     5 
// THE CORRESPONDING PINS MIGHT BE DIFFERENT IN YOUR CASE, either rewire them to match
// this or change the code to match your layout.
//
// In Arduino language 1 == HIGH, 0 == LOW
//
//      Corresponds to:  2,3,4,5,6,7,8 for pins1 (9,10,11,12,13,A0,A1,A5 for pins2)
byte digits[10][7] = { { 1,1,1,1,1,1,0 }, // = 0
                       { 0,1,1,0,0,0,0 }, // = 1
                       { 1,1,0,1,1,0,1 }, // = 2
                       { 1,1,1,1,0,0,1 }, // = 3
                       { 0,1,1,0,0,1,1 }, // = 4
                       { 1,0,1,1,0,1,1 }, // = 5
                       { 1,0,1,1,1,1,1 }, // = 6
                       { 1,1,1,0,0,0,0 }, // = 7
                       { 1,1,1,1,1,1,1 }, // = 8
                       { 1,1,1,0,0,1,1 }  // = 9
                     };


void setup() { 
	//OTHER CODE HERE

	// Set LED pins as output
	for (int i=0; i<7; i++){
		pinMode(pins1[i], OUTPUT);
		pinMode(pins2[i], OUTPUT);
	}
}
void loop() { 
	//OTHER CODE HERE

	displayDigit(23); // as an example call display function to show "23"
}


displayDigit(int num){	
	int dig1 = num / 10; // Figure out 1st digit 
			     // i.e.: 23 / 10 = 2.3 = int 2   
				      3 / 10 = 0.3 = int 0
	int dig2 = num % 10; // Figure out 2nd digit. "%" is called "mod", returns the 	        
                             // remainder of a division operation
			     // i.e.: 23 % 10 = 3
			     //       3 % 10 = 3

	// Increment through both arrays of LEDs and set the appropriate segments
	// 1(HIGH) or 0(LOW)
	for(int i=0; i<7; i++) {
	        digitalWrite(pins1[i], digits[dig1][i]);
		digitalWrite(pins2[i], digits[dig2][i]);
	}
}

// This way there is no need for ledLOW() function, no need for all the individual function to // display each digit, consequently there is less things that can go wrong.