Staking ADA not correctly rewarded?

Hello.

So I staked ~282.67 ADA on 30th June for 7 day at 17.7% APY. If my math is correct, this should result in ~9.72 ADA as reward. That means I should have ended up with 282.67 + 9.72 = 292.39. But I only have ~285.16. Please do correct me if my math is off.

Thanks

17.7% / 12 months = 1.475% / month
1.475 / 30 days = 0.0491% / day
0.0491% * 7 days = 0.3441%
282.67 * 0.003441% = 9.72 ADA

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282.67ADA @ 17.7% APY

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ADA balance after stake