Find the monthly cost for a daycare or sitter in your area. Now multiply it by the number of children you have. That is your monthly daycare cost.
Now say you got a job making $10.00 per hour (going rate around here), and work 40 hours a week. Multiply 40 hours by $10.00 per hour. That's about $400 per week. Now don't forget to take taxes out of that! Now multiply the number after taxes by 4 because that's the typical number of weeks in a month.
Now how much money was made in a month AFTER TAXES verses how much money was paid in child care in a month? Do you come out even, paying more in child care than you're making, or do you still have money left over after paying for child care?
Not every one has friends or family around to watch the kids and not SOs job has predictable hours. Just food for thought.