let answer = 0; function check(i, j) { if( i === (Math.floor(j / 10) + (j % 10))) { //console.log(i + '/' + j) answer = answer + 1; } } for (let i = 1; i <= 12; i++) { if(i === 2) { for (let j = 1; j <= 28; j++) check(i, j); } else if (i === 4 || i === 6 || i === 9 || i === 11) { for (let j = 1; j <= 30; j++) check(i, j); } else { for (let j = 1; j <= 31; j++) { check(i, j); } } } console.log(answer);