The dates of birthdays, anniversaries and their Social Security number are among the numbers that are most important to Americans, reveals the ING Retirement Number Study. But, just because the balance of their chequebook or their yearly retirement contribution isn’t most important to them, doesn’t mean they aren’t thinking about those other numbers too.

The survey, which was conducted by Ipsos, revealed that only 5% consider a financial number—one that represented what they have over who they are —as being most important to them. However, the majority of adults do think “very often” or “sometimes” about the balance of their chequing account (74%), how much they have saved and invested (72%) and how much they need for retirement (67%).

“It’s ironic that birthdays top the list of most important numbers,” says Kathleen Murphy, CEO of U.S. wealth management for ING. “As people live longer and celebrate more birthdays, they also face a greater risk of outliving their retirement savings. We hope identifying and working towards one’s retirement number will be as important as achieving each additional birthday.”

When asked what they should consider in order to accurately calculate how much they will need for retirement, 37% of people said living expenses and no other factor is cited by more than 7% of participants, such as life expectancy (7%), assets (6%), health (5%), healthcare costs (5%), and age of retirement (5%).

Despite their retirement number not being the most important to them, 30% “fully agree” and 25% “somewhat agree” that they have already calculated how much they will need to live happily once they retire. Unfortunately, 49% said figuring out how much they need is complicated and that they wouldn’t even know where to start.

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