Rekenen met datum en tijd

Aangezien \(t = 0\) overeenkomt met 1 januari, komt \(t = 295\) overeen met \(296 \text{ } \text{januari} \text{.}\)

\(296 \text{ } \text{januari}\)
\(\text{ } = 296 - 31 \text{ (januari)} = 265 \text{ } \text{februari}\)
\(\text{ } = 265 - 28 \text{ (februari)} = 237 \text{ } \text{maart}\)
\(\text{ } = 237 - 31 \text{ (maart)} = 206 \text{ } \text{april}\)
\(\text{ } = 206 - 30 \text{ (april)} = 176 \text{ } \text{mei}\)
\(\text{ } = 176 - 31 \text{ (mei)} = 145 \text{ } \text{juni}\)
\(\text{ } = 145 - 30 \text{ (juni)} = 115 \text{ } \text{juli}\)
\(\text{ } = 115 - 31 \text{ (juli)} = 84 \text{ } \text{augustus}\)
\(\text{ } = 84 - 31 \text{ (augustus)} = 53 \text{ } \text{september}\)
\(\text{ } = 53 - 30 \text{ (september)} = 23 \text{ } \text{oktober}\)

Aangezien \(t = 0\) overeenkomt met 11 februari 2022, komt \(t = 85\) overeen met \(11 + 85 = 96 \text{ } \text{februari} \text{.}\)

\(96 \text{ } \text{februari}\)
\(\text{ } = 96 - 28 \text{ (februari)} = 68 \text{ } \text{maart}\)
\(\text{ } = 68 - 31 \text{ (maart)} = 37 \text{ } \text{april}\)
\(\text{ } = 37 - 30 \text{ (april)} = 7 \text{ } \text{mei}\)
Dus bij \(t = 85\) hoort 7 mei 2022.

2 september 2018 is \(t = 0\)
30 september 2018 is \(t = 30 - 2 = 28\)
31 oktober 2018 is \(t = 28 + 31 = 59\)
30 november 2018 is \(t = 59 + 30 = 89\)
10 december 2018 is \(t = 89 + 10 = 99\)

\(t = 40\) komt dan overeen met \(\text{2005} + 40 = \text{2045} \text{.}\)

\(\text{2007}\) komt dan overeen met \(t = \text{2007} - \text{1990} = 17 \text{.}\)

De maand februari heeft \(28\) dagen (of \(29\) in een schrikkeljaar).

De \(12\)e maand van het kalenderjaar is \(\text{december} \text{.}\)

Op \(t = 5{,}626\) is het \(5 \text{ } \text{uur}\) en \(0{,}626 ⋅ 60 = 37{,}56 \text{ } \text{minuten}\) later dan \(\text{6:00} \text{ } \text{uur} \text{.}\)
Het is dan dus \(\text{11:37} \text{ } \text{uur} \text{.}\)

Om \(\text{17:04} \text{ } \text{uur}\) is het \(8 \text{ } \text{uur}\) en \(4 \text{ } \text{minuten}\) later dan \(\text{9:00} \text{ } \text{uur} \text{.}\)
Dat is dus bij \(t = 8 + {4 \over 60} = 8{,}06666... \text{.}\)

\(5{,}6 \text{ } \text{minuten} = 5{,}6 ⋅ 60 \text{ } \text{seconden} = 336 \text{ } \text{seconden}\)

\(271{,}2 \text{ } \text{uren} = 271{,}2 : 24 \text{ } \text{dagen} = 11{,}3 \text{ } \text{dagen}\)

\(0{,}58 \text{ } \text{jaar} = 0{,}58 ⋅ 12 = 6{,}96 \text{ } \text{maanden} \text{,}\) dus \(4{,}58 \text{ } \text{jaar} = 4 \text{ } \text{jaar}\) en \(7 \text{ } \text{maanden} \text{.}\)

\(8 \text{ } \text{jaar}\) en \(3 \text{ } \text{maanden} = 8 + {3 \over 12} = 8{,}25 \text{ } \text{jaar} \text{.}\)

\(8 \text{ } \text{dagen} = 8 ⋅ 24 ⋅ 3\,600 = 691\,200 \text{ } \text{seconden}\)
\(18 \text{ } \text{uren} = 18 ⋅ 3\,600 = 64\,800 \text{ } \text{seconden}\)
\(31 \text{ } \text{minuten} = 31 ⋅ 60 = 1\,860 \text{ } \text{seconden}\)
Dus \(691\,200 + 64\,800 + 1\,860 + 40 = 757\,900 \text{ } \text{seconden}\)

\(99\,818 \text{ } \text{seconden} = {99\,818 \over 24 ⋅ 60 ⋅ 60} = 1{,}155... \text{ } \text{dagen}\)
\(0{,}155... \text{ } \text{dagen} = 0{,}155... ⋅ 24 = 3{,}727... \text{ } \text{uren}\)
\(0{,}727... \text{ } \text{uren} = 0{,}727... ⋅ 60 = 43{,}633... \text{ } \text{minuten}\)
\(0{,}633... \text{ } \text{minuten} = 0{,}633... ⋅ 60 = 38 \text{ } \text{seconden}\)
Dus \(1 \text{ } \text{dagen} \text{,}\) \(3 \text{ } \text{uren} \text{,}\) \(43 \text{ } \text{minuten}\) en \(38 \text{ } \text{seconden} \text{.}\)

\(1 \text{ } \text{kwartaal} = 3 \text{ } \text{maanden}\)