Explaination for the output of the program which contradicts mathematical thinking [duplicate]

Question

#include <stdio.h>

int main() {
    float a = 0.7;
    
    if (0.7 > a) {
        printf ("Hi");
    }
    else {
        printf ("Hello");
    }
}

//outputs "Hi"

I realise that it can't be just maths and there's something more to it. Please explain why the above condition is true.