# Sum of digits of a number in PHP

## Using modulus

We can use math modulus to get the reminder of division by 10 and use it to get all digits. We are using floor() also.
Sum of all digits of a number in PHP by extracting digits and by using sticky form
``````\$n1=1234321; // Sample number
\$sum=0;
while(\$n1>0){
\$d=\$n1%10; // reminder of division
\$sum = \$sum  + \$d;
//\$n1=floor(\$n1/10); // floor value
\$n1=\$n1/10; // integer output as both are integers
}
echo \$sum;``````
Output
``16``

## User input in a form

We can ask user input and by using a sticky form and collect the number to get the sum of the digits.
``````<form method=POST action=''>
<input type=text name=n1 value='\$n1'>
<input type=submit value=Submit>
</form>";
\$n2=\$n1; // to display along with sum
\$sum=0;
while(\$n1>0){
\$d=\$n1%10;	 // reminder
\$sum=\$sum+\$d;
//\$n1=floor(\$n1/10);
\$n1=\$n1/10; // integer output as both are integers
}
echo " Sum of digits of \$n2 is \$sum";``````
We can use number ( or string ) as string and get the sum of the digits.
``````\$n1='4568'; // use string, not as number.
//\$n1=4568; // using a number . use next line also
//\$n1=\$n1.""; // converting to string
\$length=strlen(\$n1);

\$sum=0;
for(\$i=0;\$i<\$length;\$i++){
\$sum=\$sum+\$n1[\$i];
}
echo "Sum of digits of \$n1 : ".\$sum;``````
Output
``Sum of digits of 4568 : 23``
Using a sticky form
``````\$n1=\$_POST['n1'];
echo "<form method=POST action=''>
<input type=text name=n1 value='\$n1'>
<input type=submit value=Submit>
</form>";
\$length=strlen(\$n1);

\$sum=0;
for(\$i=0;\$i<\$length;\$i++){
\$sum=\$sum+\$n1[\$i];
}
echo "Sum of digits of \$n1 : ".\$sum;``````

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