Rounding、Estimating 同 Ballpark Figures:自然英文裏面嘅粗略數學

有個學生喺度練口試。題目叫佢描述佢家鄉住咗幾多人。佢僵住咗,然後講:「Three hundred and twenty-six thousand, four hundred and eighty-two people.」考官眨咗眨眼。喺現實生活裏面,冇人會用一個人口普查般精確嘅數字嚟答呢條問題。佢哋會講類似:「About three hundred thousand, give or take.」真實嘅講者會約數。真實嘅講者會估個大概。識得粗略數學嘅字眼,就係流利嘅一半。

點解咁緊要

真實對話裏面大部分數字都係估算。人工、距離、一棟大廈嘅樓齡、人群嘅規模、揸車去某處要幾耐 —— 幾乎冇一樣係精確嘅,而扮到佢精確就聽落好機械。英文有豐富嘅詞彙去講「呢個大概係嗰個數」,而揀啱個短語就話畀聽者知你係自信、唔肯定、正式,定係淨係傾緊偈。喺考試裏面,當學習者自然噉用 roughly、ballpark 或者 give or take 嚟保守表達時,考官會畀分。喺商業裏面,高層通常偏好一個快速嘅大概值多過一個精確但遲嘅答案。粗略數學係一種技巧,而唔係懶。

如果你已經讀過 Around、About、Nearly、Over、Under:英文點樣令數字冇咁精確,你就有咗啲表示方向嘅字眼。呢篇文章加上 rounding 一族 —— 嗰種「我哋唔好理啲零頭啦」嘅語言。

規律

Round up 解作將一個數字移到上一個較高嘅整數值。

• 47 rounded up to the nearest ten is 50.
• A $19.40 bill rounded up to $20.

Round down 解作將一個數字移到下一個較低嘅整數值。

• 43 rounded down to the nearest ten is 40.
• A $20.60 bill rounded down is $20.

Round to the nearest 加一個單位,就講出個精度。

• Round to the nearest dollar.
• Round to the nearest ten / hundred / thousand.
• Round to two decimal places.(喺正式或者科學語境常見。)

Round off 係一個較柔和嘅講法,意思係「等我唔好理啲精確數位啦」。

• "I'll round off to one hundred."

Ballpark 可以係名詞或者形容詞。一個 ballpark figure 係一個粗略嘅估算。In the ballpark 解作 接近啱。

• "Give me a ballpark figure for the cost."
• "Two thousand? Yeah, that's in the ballpark."

Give or take 係口語版嘅加減。

• "Fifty people, give or take."
• "Fifty people, give or take five."

Rough estimate 或者 rough guess 標示「呢個唔係最終嘅」。

• "My rough estimate is around three hours."

On the order of 較正式,喺科學同商業常見。

• "We're looking at costs on the order of one million dollars."

Somewhere in the neighborhood of 親切、稍為長,喺口語英文裏面好自然。

• "The trip cost somewhere in the neighborhood of two thousand dollars."

-ish 偷偷噉黐喺時間同整數後面。

• "I'll be there at seven-ish."
• "Two hundred-ish people came."

錯誤 / 自然 / 點解

常見情境

夾錢找餐廳數。「The total is forty-three twenty. Let's just round up to forty-five and call it tip.」真實食客幾乎永遠唔會精準噉夾。佢哋約數、畀貼士、然後行開。喺一餐隨意嘅晚飯講「the bill is forty-three twenty exactly」就感覺奇怪噉正式。

喺公司報價。主管問:「How long will this take?」教科書答案會係:「Exactly eighteen days.」自然嘅答案係:「Ballpark, two to three weeks. Give or take a couple of days if QA finds issues.」呢句話同一時間顯示自信同誠實。

隨意噉講時間。「I'll swing by eight-ish.」「Let's meet at seven-thirty-ish outside the café.」嗰個 -ish 話畀你朋友知「唔使準時企喺度望住隻錶」。佢親切、靈活、口語化。

描述人群。「There were around five hundred people at the rally, give or take a hundred.」人群數字出晒名難估,所以疊兩個保守詞 —— around 同 give or take —— 聽落自然。真實記者通常都係咁做。

估人工。「Senior engineers make somewhere in the neighborhood of a hundred and twenty thousand a year.」呢個短語標示「我唔知確切數,但我畀緊你一個有用嘅範圍」。佢係「$100K–$140K」嘅口語等價物。

大聲做粗略數學。「It's twenty-three percent of about two hundred. Call that twenty-five percent of two hundred, which is fifty. So roughly forty-five.」留意呢個竅門:講者將一個難計嘅數換成一個易計嘅,然後承認個答案係 roughly。呢個正正係流利講者處理快速心算嘅方法。

常見錯誤

• 講 round to the nearest of ten,多咗個 of。個短語係 round to the nearest ten。
• 將 give or take 同 plus or minus 溝埋。兩個都有。Plus or minus 較技術性,出現喺科學或者統計語境。Give or take 係日常嘅。唔好混埋。
• 喺 figure 用 in the ballpark。A ballpark figure 係名詞形式。In the ballpark 係慣用語。講 in the ballpark figure 就將佢哋撈埋一齊。
• 唔記得 round up 同 round down 有方向性。你唔可以 round up to a smaller number,亦唔可以 round down to a larger one。
• 想講 estimate 嘅時候講咗 estimation。兩個都係字,但喺日常口語裏面個名詞係 estimate:a rough estimate、a quick estimate、my estimate。Estimation 傾向解作 估算嘅過程,較罕見。
• 不必要噉疊保守詞:roughly about approximately ten dollars。一個保守詞就夠。
• 喺正式寫作用 -ish。Twenty-ish 喺傾偈度好掂;喺報告裏面就彆扭。
• 將 round number(一個乾淨嘅數字,例如 100、1,000)同 round numbers(解作「大概嘅數字」)搞亂。一個 round number 係精確而乾淨嘅。一個 approximate number 係未指定嘅。

迷你練習

為每格揀最自然嘅粗略數學字眼。

1. The bill came to nineteen ninety, so we just ______ to twenty and added tip.
2. I need a quick ______ for the renovation — don't worry about details yet.
3. There were ______ two hundred guests, give or take twenty.
4. The meeting starts at three-thirty, ______. Don't be exactly on time, but don't be late either.
5. Costs will run ______ ______ ______ ______ ten thousand dollars; we'll know more after the audit. (Use the formal "on the order of" form.)

總結

Round up 同 round down 講出方向。Round to the nearest 加一個單位,講出精度。Ballpark figure、rough estimate、on the order of 同 somewhere in the neighborhood of 講出信心程度。Give or take 係口語版嘅加減,而 -ish 係最上面嗰撮隨意嘅調味。真實嘅英文講者成日都估個大概 —— 學識呢啲短語,係其中一個最快令你由似一部計算機變返似一個人嘅方法。

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